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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * CFQ, or complete fairness queueing, disk scheduler.
3 *
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
6 *
Jens Axboe0fe23472006-09-04 15:41:16 +02007 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
Linus Torvalds1da177e2005-04-16 15:20:36 -07008 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07009#include <linux/module.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090010#include <linux/slab.h>
Al Viro1cc9be62006-03-18 12:29:52 -050011#include <linux/blkdev.h>
12#include <linux/elevator.h>
Randy Dunlapad5ebd22009-11-11 13:47:45 +010013#include <linux/jiffies.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/rbtree.h>
Jens Axboe22e2c502005-06-27 10:55:12 +020015#include <linux/ioprio.h>
Jens Axboe7b679132008-05-30 12:23:07 +020016#include <linux/blktrace_api.h>
Vivek Goyale98ef892010-06-18 10:39:47 -040017#include "cfq.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070018
19/*
20 * tunables
21 */
Jens Axboefe094d92008-01-31 13:08:54 +010022/* max queue in one round of service */
Shaohua Liabc3c742010-03-01 09:20:54 +010023static const int cfq_quantum = 8;
Arjan van de Ven64100092006-01-06 09:46:02 +010024static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
Jens Axboefe094d92008-01-31 13:08:54 +010025/* maximum backwards seek, in KiB */
26static const int cfq_back_max = 16 * 1024;
27/* penalty of a backwards seek */
28static const int cfq_back_penalty = 2;
Arjan van de Ven64100092006-01-06 09:46:02 +010029static const int cfq_slice_sync = HZ / 10;
Jens Axboe3b181522005-06-27 10:56:24 +020030static int cfq_slice_async = HZ / 25;
Arjan van de Ven64100092006-01-06 09:46:02 +010031static const int cfq_slice_async_rq = 2;
Jens Axboecaaa5f92006-06-16 11:23:00 +020032static int cfq_slice_idle = HZ / 125;
Corrado Zoccolo5db5d642009-10-26 22:44:04 +010033static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
34static const int cfq_hist_divisor = 4;
Jens Axboe22e2c502005-06-27 10:55:12 +020035
Jens Axboed9e76202007-04-20 14:27:50 +020036/*
Jens Axboe08717142008-01-28 11:38:15 +010037 * offset from end of service tree
Jens Axboed9e76202007-04-20 14:27:50 +020038 */
Jens Axboe08717142008-01-28 11:38:15 +010039#define CFQ_IDLE_DELAY (HZ / 5)
Jens Axboed9e76202007-04-20 14:27:50 +020040
41/*
42 * below this threshold, we consider thinktime immediate
43 */
44#define CFQ_MIN_TT (2)
45
Jens Axboe22e2c502005-06-27 10:55:12 +020046#define CFQ_SLICE_SCALE (5)
Aaron Carroll45333d52008-08-26 15:52:36 +020047#define CFQ_HW_QUEUE_MIN (5)
Vivek Goyal25bc6b02009-12-03 12:59:43 -050048#define CFQ_SERVICE_SHIFT 12
Jens Axboe22e2c502005-06-27 10:55:12 +020049
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +010050#define CFQQ_SEEK_THR (sector_t)(8 * 100)
Shaohua Lie9ce3352010-03-19 08:03:04 +010051#define CFQQ_CLOSE_THR (sector_t)(8 * 1024)
Corrado Zoccolo41647e72010-02-27 19:45:40 +010052#define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32)
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +010053#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
Shaohua Liae54abe2010-02-05 13:11:45 +010054
Jens Axboefe094d92008-01-31 13:08:54 +010055#define RQ_CIC(rq) \
56 ((struct cfq_io_context *) (rq)->elevator_private)
Jens Axboe7b679132008-05-30 12:23:07 +020057#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +020058#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private3)
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
Christoph Lametere18b8902006-12-06 20:33:20 -080060static struct kmem_cache *cfq_pool;
61static struct kmem_cache *cfq_ioc_pool;
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
Tejun Heo245b2e72009-06-24 15:13:48 +090063static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
Al Viro334e94d2006-03-18 15:05:53 -050064static struct completion *ioc_gone;
Jens Axboe9a11b4e2008-05-29 09:32:08 +020065static DEFINE_SPINLOCK(ioc_gone_lock);
Al Viro334e94d2006-03-18 15:05:53 -050066
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +040067static DEFINE_SPINLOCK(cic_index_lock);
68static DEFINE_IDA(cic_index_ida);
69
Jens Axboe22e2c502005-06-27 10:55:12 +020070#define CFQ_PRIO_LISTS IOPRIO_BE_NR
71#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
Jens Axboe22e2c502005-06-27 10:55:12 +020072#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
73
Jens Axboe206dc692006-03-28 13:03:44 +020074#define sample_valid(samples) ((samples) > 80)
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -050075#define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
Jens Axboe206dc692006-03-28 13:03:44 +020076
Jens Axboe22e2c502005-06-27 10:55:12 +020077/*
Jens Axboecc09e292007-04-26 12:53:50 +020078 * Most of our rbtree usage is for sorting with min extraction, so
79 * if we cache the leftmost node we don't have to walk down the tree
80 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
81 * move this into the elevator for the rq sorting as well.
82 */
83struct cfq_rb_root {
84 struct rb_root rb;
85 struct rb_node *left;
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +010086 unsigned count;
Richard Kennedy73e9ffd2010-03-01 10:50:20 +010087 unsigned total_weight;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -050088 u64 min_vdisktime;
Vivek Goyal25bc6b02009-12-03 12:59:43 -050089 struct rb_node *active;
Jens Axboecc09e292007-04-26 12:53:50 +020090};
Richard Kennedy73e9ffd2010-03-01 10:50:20 +010091#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
92 .count = 0, .min_vdisktime = 0, }
Jens Axboecc09e292007-04-26 12:53:50 +020093
94/*
Jens Axboe6118b702009-06-30 09:34:12 +020095 * Per process-grouping structure
96 */
97struct cfq_queue {
98 /* reference count */
99 atomic_t ref;
100 /* various state flags, see below */
101 unsigned int flags;
102 /* parent cfq_data */
103 struct cfq_data *cfqd;
104 /* service_tree member */
105 struct rb_node rb_node;
106 /* service_tree key */
107 unsigned long rb_key;
108 /* prio tree member */
109 struct rb_node p_node;
110 /* prio tree root we belong to, if any */
111 struct rb_root *p_root;
112 /* sorted list of pending requests */
113 struct rb_root sort_list;
114 /* if fifo isn't expired, next request to serve */
115 struct request *next_rq;
116 /* requests queued in sort_list */
117 int queued[2];
118 /* currently allocated requests */
119 int allocated[2];
120 /* fifo list of requests in sort_list */
121 struct list_head fifo;
122
Vivek Goyaldae739e2009-12-03 12:59:45 -0500123 /* time when queue got scheduled in to dispatch first request. */
124 unsigned long dispatch_start;
Vivek Goyalf75edf22009-12-03 12:59:53 -0500125 unsigned int allocated_slice;
Richard Kennedyc4081ba2010-02-22 13:49:24 +0100126 unsigned int slice_dispatch;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500127 /* time when first request from queue completed and slice started. */
128 unsigned long slice_start;
Jens Axboe6118b702009-06-30 09:34:12 +0200129 unsigned long slice_end;
130 long slice_resid;
Jens Axboe6118b702009-06-30 09:34:12 +0200131
132 /* pending metadata requests */
133 int meta_pending;
134 /* number of requests that are on the dispatch list or inside driver */
135 int dispatched;
136
137 /* io prio of this group */
138 unsigned short ioprio, org_ioprio;
139 unsigned short ioprio_class, org_ioprio_class;
140
Richard Kennedyc4081ba2010-02-22 13:49:24 +0100141 pid_t pid;
142
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +0100143 u32 seek_history;
Jeff Moyerb2c18e12009-10-23 17:14:49 -0400144 sector_t last_request_pos;
145
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +0100146 struct cfq_rb_root *service_tree;
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -0400147 struct cfq_queue *new_cfqq;
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500148 struct cfq_group *cfqg;
Vivek Goyalae30c282009-12-03 12:59:55 -0500149 struct cfq_group *orig_cfqg;
Jens Axboe6118b702009-06-30 09:34:12 +0200150};
151
152/*
Corrado Zoccolo718eee02009-10-26 22:45:29 +0100153 * First index in the service_trees.
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100154 * IDLE is handled separately, so it has negative index
155 */
156enum wl_prio_t {
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100157 BE_WORKLOAD = 0,
Vivek Goyal615f0252009-12-03 12:59:39 -0500158 RT_WORKLOAD = 1,
159 IDLE_WORKLOAD = 2,
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100160};
161
162/*
Corrado Zoccolo718eee02009-10-26 22:45:29 +0100163 * Second index in the service_trees.
164 */
165enum wl_type_t {
166 ASYNC_WORKLOAD = 0,
167 SYNC_NOIDLE_WORKLOAD = 1,
168 SYNC_WORKLOAD = 2
169};
170
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500171/* This is per cgroup per device grouping structure */
172struct cfq_group {
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500173 /* group service_tree member */
174 struct rb_node rb_node;
175
176 /* group service_tree key */
177 u64 vdisktime;
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500178 unsigned int weight;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500179 bool on_st;
180
181 /* number of cfqq currently on this group */
182 int nr_cfqq;
183
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500184 /* Per group busy queus average. Useful for workload slice calc. */
185 unsigned int busy_queues_avg[2];
Jens Axboe22e2c502005-06-27 10:55:12 +0200186 /*
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100187 * rr lists of queues with requests, onle rr for each priority class.
188 * Counts are embedded in the cfq_rb_root
Jens Axboe22e2c502005-06-27 10:55:12 +0200189 */
Corrado Zoccolo718eee02009-10-26 22:45:29 +0100190 struct cfq_rb_root service_trees[2][3];
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100191 struct cfq_rb_root service_tree_idle;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500192
193 unsigned long saved_workload_slice;
194 enum wl_type_t saved_workload;
195 enum wl_prio_t saved_serving_prio;
Vivek Goyal25fb5162009-12-03 12:59:46 -0500196 struct blkio_group blkg;
197#ifdef CONFIG_CFQ_GROUP_IOSCHED
198 struct hlist_node cfqd_node;
Vivek Goyalb1c35762009-12-03 12:59:47 -0500199 atomic_t ref;
Vivek Goyal25fb5162009-12-03 12:59:46 -0500200#endif
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500201};
202
203/*
204 * Per block device queue structure
205 */
206struct cfq_data {
207 struct request_queue *queue;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500208 /* Root service tree for cfq_groups */
209 struct cfq_rb_root grp_service_tree;
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500210 struct cfq_group root_group;
211
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100212 /*
213 * The priority currently being served
214 */
215 enum wl_prio_t serving_prio;
Corrado Zoccolo718eee02009-10-26 22:45:29 +0100216 enum wl_type_t serving_type;
217 unsigned long workload_expires;
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500218 struct cfq_group *serving_group;
Corrado Zoccolo8e550632009-11-26 10:02:58 +0100219 bool noidle_tree_requires_idle;
Jens Axboea36e71f2009-04-15 12:15:11 +0200220
221 /*
222 * Each priority tree is sorted by next_request position. These
223 * trees are used when determining if two or more queues are
224 * interleaving requests (see cfq_close_cooperator).
225 */
226 struct rb_root prio_trees[CFQ_PRIO_LISTS];
227
Jens Axboe22e2c502005-06-27 10:55:12 +0200228 unsigned int busy_queues;
229
Corrado Zoccolo53c583d2010-02-28 19:45:05 +0100230 int rq_in_driver;
231 int rq_in_flight[2];
Aaron Carroll45333d52008-08-26 15:52:36 +0200232
233 /*
234 * queue-depth detection
235 */
236 int rq_queued;
Jens Axboe25776e32006-06-01 10:12:26 +0200237 int hw_tag;
Corrado Zoccoloe459dd02009-11-26 10:02:57 +0100238 /*
239 * hw_tag can be
240 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
241 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
242 * 0 => no NCQ
243 */
244 int hw_tag_est_depth;
245 unsigned int hw_tag_samples;
Jens Axboe22e2c502005-06-27 10:55:12 +0200246
247 /*
Jens Axboe22e2c502005-06-27 10:55:12 +0200248 * idle window management
249 */
250 struct timer_list idle_slice_timer;
Jens Axboe23e018a2009-10-05 08:52:35 +0200251 struct work_struct unplug_work;
Jens Axboe22e2c502005-06-27 10:55:12 +0200252
253 struct cfq_queue *active_queue;
254 struct cfq_io_context *active_cic;
Jens Axboe22e2c502005-06-27 10:55:12 +0200255
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +0200256 /*
257 * async queue for each priority case
258 */
259 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
260 struct cfq_queue *async_idle_cfqq;
Jens Axboe15c31be2007-07-10 13:43:25 +0200261
Jens Axboe6d048f52007-04-25 12:44:27 +0200262 sector_t last_position;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 /*
265 * tunables, see top of file
266 */
267 unsigned int cfq_quantum;
Jens Axboe22e2c502005-06-27 10:55:12 +0200268 unsigned int cfq_fifo_expire[2];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 unsigned int cfq_back_penalty;
270 unsigned int cfq_back_max;
Jens Axboe22e2c502005-06-27 10:55:12 +0200271 unsigned int cfq_slice[2];
272 unsigned int cfq_slice_async_rq;
273 unsigned int cfq_slice_idle;
Jens Axboe963b72f2009-10-03 19:42:18 +0200274 unsigned int cfq_latency;
Vivek Goyalae30c282009-12-03 12:59:55 -0500275 unsigned int cfq_group_isolation;
Al Virod9ff4182006-03-18 13:51:22 -0500276
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +0400277 unsigned int cic_index;
Al Virod9ff4182006-03-18 13:51:22 -0500278 struct list_head cic_list;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279
Jens Axboe6118b702009-06-30 09:34:12 +0200280 /*
281 * Fallback dummy cfqq for extreme OOM conditions
282 */
283 struct cfq_queue oom_cfqq;
Vivek Goyal365722b2009-10-03 15:21:27 +0200284
Corrado Zoccolo573412b2009-12-06 11:48:52 +0100285 unsigned long last_delayed_sync;
Vivek Goyal25fb5162009-12-03 12:59:46 -0500286
287 /* List of cfq groups being managed on this device*/
288 struct hlist_head cfqg_list;
Jens Axboebb729bc2009-12-06 09:54:19 +0100289 struct rcu_head rcu;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290};
291
Vivek Goyal25fb5162009-12-03 12:59:46 -0500292static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
293
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500294static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
295 enum wl_prio_t prio,
Vivek Goyal65b32a52009-12-16 17:52:59 -0500296 enum wl_type_t type)
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100297{
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500298 if (!cfqg)
299 return NULL;
300
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100301 if (prio == IDLE_WORKLOAD)
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500302 return &cfqg->service_tree_idle;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100303
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500304 return &cfqg->service_trees[prio][type];
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100305}
306
Jens Axboe3b181522005-06-27 10:56:24 +0200307enum cfqq_state_flags {
Jens Axboeb0b8d742007-01-19 11:35:30 +1100308 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
309 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
Jens Axboeb0291952009-04-07 11:38:31 +0200310 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
Jens Axboeb0b8d742007-01-19 11:35:30 +1100311 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
Jens Axboeb0b8d742007-01-19 11:35:30 +1100312 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
313 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
314 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
Jens Axboe44f7c162007-01-19 11:51:58 +1100315 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
Vasily Tarasov91fac312007-04-25 12:29:51 +0200316 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
Jeff Moyerb3b6d042009-10-23 17:14:51 -0400317 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
Shaohua Liae54abe2010-02-05 13:11:45 +0100318 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
Corrado Zoccolo76280af2009-11-26 10:02:58 +0100319 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
Vivek Goyalf75edf22009-12-03 12:59:53 -0500320 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
Jens Axboe3b181522005-06-27 10:56:24 +0200321};
322
323#define CFQ_CFQQ_FNS(name) \
324static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
325{ \
Jens Axboefe094d92008-01-31 13:08:54 +0100326 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
Jens Axboe3b181522005-06-27 10:56:24 +0200327} \
328static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
329{ \
Jens Axboefe094d92008-01-31 13:08:54 +0100330 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
Jens Axboe3b181522005-06-27 10:56:24 +0200331} \
332static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
333{ \
Jens Axboefe094d92008-01-31 13:08:54 +0100334 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
Jens Axboe3b181522005-06-27 10:56:24 +0200335}
336
337CFQ_CFQQ_FNS(on_rr);
338CFQ_CFQQ_FNS(wait_request);
Jens Axboeb0291952009-04-07 11:38:31 +0200339CFQ_CFQQ_FNS(must_dispatch);
Jens Axboe3b181522005-06-27 10:56:24 +0200340CFQ_CFQQ_FNS(must_alloc_slice);
Jens Axboe3b181522005-06-27 10:56:24 +0200341CFQ_CFQQ_FNS(fifo_expire);
342CFQ_CFQQ_FNS(idle_window);
343CFQ_CFQQ_FNS(prio_changed);
Jens Axboe44f7c162007-01-19 11:51:58 +1100344CFQ_CFQQ_FNS(slice_new);
Vasily Tarasov91fac312007-04-25 12:29:51 +0200345CFQ_CFQQ_FNS(sync);
Jens Axboea36e71f2009-04-15 12:15:11 +0200346CFQ_CFQQ_FNS(coop);
Shaohua Liae54abe2010-02-05 13:11:45 +0100347CFQ_CFQQ_FNS(split_coop);
Corrado Zoccolo76280af2009-11-26 10:02:58 +0100348CFQ_CFQQ_FNS(deep);
Vivek Goyalf75edf22009-12-03 12:59:53 -0500349CFQ_CFQQ_FNS(wait_busy);
Jens Axboe3b181522005-06-27 10:56:24 +0200350#undef CFQ_CFQQ_FNS
351
Vivek Goyalafc24d42010-04-26 19:27:56 +0200352#ifdef CONFIG_CFQ_GROUP_IOSCHED
Vivek Goyal2868ef72009-12-03 12:59:48 -0500353#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
354 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
355 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
356 blkg_path(&(cfqq)->cfqg->blkg), ##args);
357
358#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
359 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
360 blkg_path(&(cfqg)->blkg), ##args); \
361
362#else
Jens Axboe7b679132008-05-30 12:23:07 +0200363#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
364 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
Vivek Goyal2868ef72009-12-03 12:59:48 -0500365#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
366#endif
Jens Axboe7b679132008-05-30 12:23:07 +0200367#define cfq_log(cfqd, fmt, args...) \
368 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
369
Vivek Goyal615f0252009-12-03 12:59:39 -0500370/* Traverses through cfq group service trees */
371#define for_each_cfqg_st(cfqg, i, j, st) \
372 for (i = 0; i <= IDLE_WORKLOAD; i++) \
373 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
374 : &cfqg->service_tree_idle; \
375 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
376 (i == IDLE_WORKLOAD && j == 0); \
377 j++, st = i < IDLE_WORKLOAD ? \
378 &cfqg->service_trees[i][j]: NULL) \
379
380
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100381static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
382{
383 if (cfq_class_idle(cfqq))
384 return IDLE_WORKLOAD;
385 if (cfq_class_rt(cfqq))
386 return RT_WORKLOAD;
387 return BE_WORKLOAD;
388}
389
Corrado Zoccolo718eee02009-10-26 22:45:29 +0100390
391static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
392{
393 if (!cfq_cfqq_sync(cfqq))
394 return ASYNC_WORKLOAD;
395 if (!cfq_cfqq_idle_window(cfqq))
396 return SYNC_NOIDLE_WORKLOAD;
397 return SYNC_WORKLOAD;
398}
399
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500400static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
401 struct cfq_data *cfqd,
402 struct cfq_group *cfqg)
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100403{
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500404 if (wl == IDLE_WORKLOAD)
405 return cfqg->service_tree_idle.count;
406
407 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
408 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
409 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +0100410}
411
Vivek Goyalf26bd1f2009-12-03 12:59:54 -0500412static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
413 struct cfq_group *cfqg)
414{
415 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
416 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
417}
418
Jens Axboe165125e2007-07-24 09:28:11 +0200419static void cfq_dispatch_insert(struct request_queue *, struct request *);
Jens Axboea6151c32009-10-07 20:02:57 +0200420static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
Jens Axboefd0928d2008-01-24 08:52:45 +0100421 struct io_context *, gfp_t);
Jens Axboe4ac845a2008-01-24 08:44:49 +0100422static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
Vasily Tarasov91fac312007-04-25 12:29:51 +0200423 struct io_context *);
424
425static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
Jens Axboea6151c32009-10-07 20:02:57 +0200426 bool is_sync)
Vasily Tarasov91fac312007-04-25 12:29:51 +0200427{
Jens Axboea6151c32009-10-07 20:02:57 +0200428 return cic->cfqq[is_sync];
Vasily Tarasov91fac312007-04-25 12:29:51 +0200429}
430
431static inline void cic_set_cfqq(struct cfq_io_context *cic,
Jens Axboea6151c32009-10-07 20:02:57 +0200432 struct cfq_queue *cfqq, bool is_sync)
Vasily Tarasov91fac312007-04-25 12:29:51 +0200433{
Jens Axboea6151c32009-10-07 20:02:57 +0200434 cic->cfqq[is_sync] = cfqq;
Vasily Tarasov91fac312007-04-25 12:29:51 +0200435}
436
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +0400437#define CIC_DEAD_KEY 1ul
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +0400438#define CIC_DEAD_INDEX_SHIFT 1
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +0400439
440static inline void *cfqd_dead_key(struct cfq_data *cfqd)
441{
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +0400442 return (void *)(cfqd->cic_index << CIC_DEAD_INDEX_SHIFT | CIC_DEAD_KEY);
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +0400443}
444
445static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
446{
447 struct cfq_data *cfqd = cic->key;
448
449 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
450 return NULL;
451
452 return cfqd;
453}
454
Vasily Tarasov91fac312007-04-25 12:29:51 +0200455/*
456 * We regard a request as SYNC, if it's either a read or has the SYNC bit
457 * set (in which case it could also be direct WRITE).
458 */
Jens Axboea6151c32009-10-07 20:02:57 +0200459static inline bool cfq_bio_sync(struct bio *bio)
Vasily Tarasov91fac312007-04-25 12:29:51 +0200460{
Jens Axboea6151c32009-10-07 20:02:57 +0200461 return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO);
Vasily Tarasov91fac312007-04-25 12:29:51 +0200462}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464/*
Andrew Morton99f95e52005-06-27 20:14:05 -0700465 * scheduler run of queue, if there are requests pending and no one in the
466 * driver that will restart queueing
467 */
Jens Axboe23e018a2009-10-05 08:52:35 +0200468static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
Andrew Morton99f95e52005-06-27 20:14:05 -0700469{
Jens Axboe7b679132008-05-30 12:23:07 +0200470 if (cfqd->busy_queues) {
471 cfq_log(cfqd, "schedule dispatch");
Jens Axboe23e018a2009-10-05 08:52:35 +0200472 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
Jens Axboe7b679132008-05-30 12:23:07 +0200473 }
Andrew Morton99f95e52005-06-27 20:14:05 -0700474}
475
Jens Axboe165125e2007-07-24 09:28:11 +0200476static int cfq_queue_empty(struct request_queue *q)
Andrew Morton99f95e52005-06-27 20:14:05 -0700477{
478 struct cfq_data *cfqd = q->elevator->elevator_data;
479
Vivek Goyalf04a6422009-12-03 12:59:40 -0500480 return !cfqd->rq_queued;
Andrew Morton99f95e52005-06-27 20:14:05 -0700481}
482
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483/*
Jens Axboe44f7c162007-01-19 11:51:58 +1100484 * Scale schedule slice based on io priority. Use the sync time slice only
485 * if a queue is marked sync and has sync io queued. A sync queue with async
486 * io only, should not get full sync slice length.
487 */
Jens Axboea6151c32009-10-07 20:02:57 +0200488static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
Jens Axboed9e76202007-04-20 14:27:50 +0200489 unsigned short prio)
490{
491 const int base_slice = cfqd->cfq_slice[sync];
492
493 WARN_ON(prio >= IOPRIO_BE_NR);
494
495 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
496}
497
Jens Axboe44f7c162007-01-19 11:51:58 +1100498static inline int
499cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
500{
Jens Axboed9e76202007-04-20 14:27:50 +0200501 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
Jens Axboe44f7c162007-01-19 11:51:58 +1100502}
503
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500504static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
505{
506 u64 d = delta << CFQ_SERVICE_SHIFT;
507
508 d = d * BLKIO_WEIGHT_DEFAULT;
509 do_div(d, cfqg->weight);
510 return d;
511}
512
513static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
514{
515 s64 delta = (s64)(vdisktime - min_vdisktime);
516 if (delta > 0)
517 min_vdisktime = vdisktime;
518
519 return min_vdisktime;
520}
521
522static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
523{
524 s64 delta = (s64)(vdisktime - min_vdisktime);
525 if (delta < 0)
526 min_vdisktime = vdisktime;
527
528 return min_vdisktime;
529}
530
531static void update_min_vdisktime(struct cfq_rb_root *st)
532{
533 u64 vdisktime = st->min_vdisktime;
534 struct cfq_group *cfqg;
535
536 if (st->active) {
537 cfqg = rb_entry_cfqg(st->active);
538 vdisktime = cfqg->vdisktime;
539 }
540
541 if (st->left) {
542 cfqg = rb_entry_cfqg(st->left);
543 vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
544 }
545
546 st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
547}
548
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100549/*
550 * get averaged number of queues of RT/BE priority.
551 * average is updated, with a formula that gives more weight to higher numbers,
552 * to quickly follows sudden increases and decrease slowly
553 */
554
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500555static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
556 struct cfq_group *cfqg, bool rt)
Jens Axboe58696192009-10-28 09:27:07 +0100557{
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100558 unsigned min_q, max_q;
559 unsigned mult = cfq_hist_divisor - 1;
560 unsigned round = cfq_hist_divisor / 2;
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500561 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100562
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500563 min_q = min(cfqg->busy_queues_avg[rt], busy);
564 max_q = max(cfqg->busy_queues_avg[rt], busy);
565 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100566 cfq_hist_divisor;
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500567 return cfqg->busy_queues_avg[rt];
568}
569
570static inline unsigned
571cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
572{
573 struct cfq_rb_root *st = &cfqd->grp_service_tree;
574
575 return cfq_target_latency * cfqg->weight / st->total_weight;
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100576}
577
Jens Axboe44f7c162007-01-19 11:51:58 +1100578static inline void
579cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
580{
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100581 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
582 if (cfqd->cfq_latency) {
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500583 /*
584 * interested queues (we consider only the ones with the same
585 * priority class in the cfq group)
586 */
587 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
588 cfq_class_rt(cfqq));
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100589 unsigned sync_slice = cfqd->cfq_slice[1];
590 unsigned expect_latency = sync_slice * iq;
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500591 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
592
593 if (expect_latency > group_slice) {
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100594 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
595 /* scale low_slice according to IO priority
596 * and sync vs async */
597 unsigned low_slice =
598 min(slice, base_low_slice * slice / sync_slice);
599 /* the adapted slice value is scaled to fit all iqs
600 * into the target latency */
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500601 slice = max(slice * group_slice / expect_latency,
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100602 low_slice);
603 }
604 }
Vivek Goyaldae739e2009-12-03 12:59:45 -0500605 cfqq->slice_start = jiffies;
Corrado Zoccolo5db5d642009-10-26 22:44:04 +0100606 cfqq->slice_end = jiffies + slice;
Vivek Goyalf75edf22009-12-03 12:59:53 -0500607 cfqq->allocated_slice = slice;
Jens Axboe7b679132008-05-30 12:23:07 +0200608 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
Jens Axboe44f7c162007-01-19 11:51:58 +1100609}
610
611/*
612 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
613 * isn't valid until the first request from the dispatch is activated
614 * and the slice time set.
615 */
Jens Axboea6151c32009-10-07 20:02:57 +0200616static inline bool cfq_slice_used(struct cfq_queue *cfqq)
Jens Axboe44f7c162007-01-19 11:51:58 +1100617{
618 if (cfq_cfqq_slice_new(cfqq))
619 return 0;
620 if (time_before(jiffies, cfqq->slice_end))
621 return 0;
622
623 return 1;
624}
625
626/*
Jens Axboe5e705372006-07-13 12:39:25 +0200627 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 * We choose the request that is closest to the head right now. Distance
Andreas Mohre8a99052006-03-28 08:59:49 +0200629 * behind the head is penalized and only allowed to a certain extent.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 */
Jens Axboe5e705372006-07-13 12:39:25 +0200631static struct request *
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +0100632cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633{
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +0100634 sector_t s1, s2, d1 = 0, d2 = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 unsigned long back_max;
Andreas Mohre8a99052006-03-28 08:59:49 +0200636#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
637#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
638 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639
Jens Axboe5e705372006-07-13 12:39:25 +0200640 if (rq1 == NULL || rq1 == rq2)
641 return rq2;
642 if (rq2 == NULL)
643 return rq1;
Jens Axboe9c2c38a2005-08-24 14:57:54 +0200644
Jens Axboe5e705372006-07-13 12:39:25 +0200645 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
646 return rq1;
647 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
648 return rq2;
Jens Axboe374f84a2006-07-23 01:42:19 +0200649 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
650 return rq1;
651 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
652 return rq2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653
Tejun Heo83096eb2009-05-07 22:24:39 +0900654 s1 = blk_rq_pos(rq1);
655 s2 = blk_rq_pos(rq2);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657 /*
658 * by definition, 1KiB is 2 sectors
659 */
660 back_max = cfqd->cfq_back_max * 2;
661
662 /*
663 * Strict one way elevator _except_ in the case where we allow
664 * short backward seeks which are biased as twice the cost of a
665 * similar forward seek.
666 */
667 if (s1 >= last)
668 d1 = s1 - last;
669 else if (s1 + back_max >= last)
670 d1 = (last - s1) * cfqd->cfq_back_penalty;
671 else
Andreas Mohre8a99052006-03-28 08:59:49 +0200672 wrap |= CFQ_RQ1_WRAP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673
674 if (s2 >= last)
675 d2 = s2 - last;
676 else if (s2 + back_max >= last)
677 d2 = (last - s2) * cfqd->cfq_back_penalty;
678 else
Andreas Mohre8a99052006-03-28 08:59:49 +0200679 wrap |= CFQ_RQ2_WRAP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680
681 /* Found required data */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682
Andreas Mohre8a99052006-03-28 08:59:49 +0200683 /*
684 * By doing switch() on the bit mask "wrap" we avoid having to
685 * check two variables for all permutations: --> faster!
686 */
687 switch (wrap) {
Jens Axboe5e705372006-07-13 12:39:25 +0200688 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
Andreas Mohre8a99052006-03-28 08:59:49 +0200689 if (d1 < d2)
Jens Axboe5e705372006-07-13 12:39:25 +0200690 return rq1;
Andreas Mohre8a99052006-03-28 08:59:49 +0200691 else if (d2 < d1)
Jens Axboe5e705372006-07-13 12:39:25 +0200692 return rq2;
Andreas Mohre8a99052006-03-28 08:59:49 +0200693 else {
694 if (s1 >= s2)
Jens Axboe5e705372006-07-13 12:39:25 +0200695 return rq1;
Andreas Mohre8a99052006-03-28 08:59:49 +0200696 else
Jens Axboe5e705372006-07-13 12:39:25 +0200697 return rq2;
Andreas Mohre8a99052006-03-28 08:59:49 +0200698 }
699
700 case CFQ_RQ2_WRAP:
Jens Axboe5e705372006-07-13 12:39:25 +0200701 return rq1;
Andreas Mohre8a99052006-03-28 08:59:49 +0200702 case CFQ_RQ1_WRAP:
Jens Axboe5e705372006-07-13 12:39:25 +0200703 return rq2;
704 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
Andreas Mohre8a99052006-03-28 08:59:49 +0200705 default:
706 /*
707 * Since both rqs are wrapped,
708 * start with the one that's further behind head
709 * (--> only *one* back seek required),
710 * since back seek takes more time than forward.
711 */
712 if (s1 <= s2)
Jens Axboe5e705372006-07-13 12:39:25 +0200713 return rq1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714 else
Jens Axboe5e705372006-07-13 12:39:25 +0200715 return rq2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716 }
717}
718
Jens Axboe498d3aa2007-04-26 12:54:48 +0200719/*
720 * The below is leftmost cache rbtree addon
721 */
Jens Axboe08717142008-01-28 11:38:15 +0100722static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
Jens Axboecc09e292007-04-26 12:53:50 +0200723{
Vivek Goyal615f0252009-12-03 12:59:39 -0500724 /* Service tree is empty */
725 if (!root->count)
726 return NULL;
727
Jens Axboecc09e292007-04-26 12:53:50 +0200728 if (!root->left)
729 root->left = rb_first(&root->rb);
730
Jens Axboe08717142008-01-28 11:38:15 +0100731 if (root->left)
732 return rb_entry(root->left, struct cfq_queue, rb_node);
733
734 return NULL;
Jens Axboecc09e292007-04-26 12:53:50 +0200735}
736
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500737static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
738{
739 if (!root->left)
740 root->left = rb_first(&root->rb);
741
742 if (root->left)
743 return rb_entry_cfqg(root->left);
744
745 return NULL;
746}
747
Jens Axboea36e71f2009-04-15 12:15:11 +0200748static void rb_erase_init(struct rb_node *n, struct rb_root *root)
749{
750 rb_erase(n, root);
751 RB_CLEAR_NODE(n);
752}
753
Jens Axboecc09e292007-04-26 12:53:50 +0200754static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
755{
756 if (root->left == n)
757 root->left = NULL;
Jens Axboea36e71f2009-04-15 12:15:11 +0200758 rb_erase_init(n, &root->rb);
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +0100759 --root->count;
Jens Axboecc09e292007-04-26 12:53:50 +0200760}
761
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762/*
763 * would be nice to take fifo expire time into account as well
764 */
Jens Axboe5e705372006-07-13 12:39:25 +0200765static struct request *
766cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
767 struct request *last)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768{
Jens Axboe21183b02006-07-13 12:33:14 +0200769 struct rb_node *rbnext = rb_next(&last->rb_node);
770 struct rb_node *rbprev = rb_prev(&last->rb_node);
Jens Axboe5e705372006-07-13 12:39:25 +0200771 struct request *next = NULL, *prev = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700772
Jens Axboe21183b02006-07-13 12:33:14 +0200773 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774
775 if (rbprev)
Jens Axboe5e705372006-07-13 12:39:25 +0200776 prev = rb_entry_rq(rbprev);
Jens Axboe21183b02006-07-13 12:33:14 +0200777
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 if (rbnext)
Jens Axboe5e705372006-07-13 12:39:25 +0200779 next = rb_entry_rq(rbnext);
Jens Axboe21183b02006-07-13 12:33:14 +0200780 else {
781 rbnext = rb_first(&cfqq->sort_list);
782 if (rbnext && rbnext != &last->rb_node)
Jens Axboe5e705372006-07-13 12:39:25 +0200783 next = rb_entry_rq(rbnext);
Jens Axboe21183b02006-07-13 12:33:14 +0200784 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +0100786 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787}
788
Jens Axboed9e76202007-04-20 14:27:50 +0200789static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
790 struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791{
Jens Axboed9e76202007-04-20 14:27:50 +0200792 /*
793 * just an approximation, should be ok.
794 */
Vivek Goyalcdb16e82009-12-03 12:59:38 -0500795 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
Jens Axboe464191c2009-11-30 09:38:13 +0100796 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
Jens Axboed9e76202007-04-20 14:27:50 +0200797}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500799static inline s64
800cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
801{
802 return cfqg->vdisktime - st->min_vdisktime;
803}
804
805static void
806__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
807{
808 struct rb_node **node = &st->rb.rb_node;
809 struct rb_node *parent = NULL;
810 struct cfq_group *__cfqg;
811 s64 key = cfqg_key(st, cfqg);
812 int left = 1;
813
814 while (*node != NULL) {
815 parent = *node;
816 __cfqg = rb_entry_cfqg(parent);
817
818 if (key < cfqg_key(st, __cfqg))
819 node = &parent->rb_left;
820 else {
821 node = &parent->rb_right;
822 left = 0;
823 }
824 }
825
826 if (left)
827 st->left = &cfqg->rb_node;
828
829 rb_link_node(&cfqg->rb_node, parent, node);
830 rb_insert_color(&cfqg->rb_node, &st->rb);
831}
832
833static void
834cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
835{
836 struct cfq_rb_root *st = &cfqd->grp_service_tree;
837 struct cfq_group *__cfqg;
838 struct rb_node *n;
839
840 cfqg->nr_cfqq++;
841 if (cfqg->on_st)
842 return;
843
844 /*
845 * Currently put the group at the end. Later implement something
846 * so that groups get lesser vtime based on their weights, so that
847 * if group does not loose all if it was not continously backlogged.
848 */
849 n = rb_last(&st->rb);
850 if (n) {
851 __cfqg = rb_entry_cfqg(n);
852 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
853 } else
854 cfqg->vdisktime = st->min_vdisktime;
855
856 __cfq_group_service_tree_add(st, cfqg);
857 cfqg->on_st = true;
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500858 st->total_weight += cfqg->weight;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500859}
860
861static void
862cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
863{
864 struct cfq_rb_root *st = &cfqd->grp_service_tree;
865
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500866 if (st->active == &cfqg->rb_node)
867 st->active = NULL;
868
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500869 BUG_ON(cfqg->nr_cfqq < 1);
870 cfqg->nr_cfqq--;
Vivek Goyal25bc6b02009-12-03 12:59:43 -0500871
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500872 /* If there are other cfq queues under this group, don't delete it */
873 if (cfqg->nr_cfqq)
874 return;
875
Vivek Goyal2868ef72009-12-03 12:59:48 -0500876 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500877 cfqg->on_st = false;
Vivek Goyal58ff82f2009-12-03 12:59:44 -0500878 st->total_weight -= cfqg->weight;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500879 if (!RB_EMPTY_NODE(&cfqg->rb_node))
880 cfq_rb_erase(&cfqg->rb_node, st);
Vivek Goyaldae739e2009-12-03 12:59:45 -0500881 cfqg->saved_workload_slice = 0;
Vivek Goyale98ef892010-06-18 10:39:47 -0400882 cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
Vivek Goyaldae739e2009-12-03 12:59:45 -0500883}
884
885static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
886{
Vivek Goyalf75edf22009-12-03 12:59:53 -0500887 unsigned int slice_used;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500888
889 /*
890 * Queue got expired before even a single request completed or
891 * got expired immediately after first request completion.
892 */
893 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
894 /*
895 * Also charge the seek time incurred to the group, otherwise
896 * if there are mutiple queues in the group, each can dispatch
897 * a single request on seeky media and cause lots of seek time
898 * and group will never know it.
899 */
900 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
901 1);
902 } else {
903 slice_used = jiffies - cfqq->slice_start;
Vivek Goyalf75edf22009-12-03 12:59:53 -0500904 if (slice_used > cfqq->allocated_slice)
905 slice_used = cfqq->allocated_slice;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500906 }
907
Divyesh Shah9a0785b2010-04-01 15:01:04 -0700908 cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u", slice_used);
Vivek Goyaldae739e2009-12-03 12:59:45 -0500909 return slice_used;
910}
911
912static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
Vivek Goyale5ff0822010-04-26 19:25:11 +0200913 struct cfq_queue *cfqq)
Vivek Goyaldae739e2009-12-03 12:59:45 -0500914{
915 struct cfq_rb_root *st = &cfqd->grp_service_tree;
Vivek Goyalf26bd1f2009-12-03 12:59:54 -0500916 unsigned int used_sl, charge_sl;
917 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
918 - cfqg->service_tree_idle.count;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500919
Vivek Goyalf26bd1f2009-12-03 12:59:54 -0500920 BUG_ON(nr_sync < 0);
921 used_sl = charge_sl = cfq_cfqq_slice_usage(cfqq);
922
923 if (!cfq_cfqq_sync(cfqq) && !nr_sync)
924 charge_sl = cfqq->allocated_slice;
Vivek Goyaldae739e2009-12-03 12:59:45 -0500925
926 /* Can't update vdisktime while group is on service tree */
927 cfq_rb_erase(&cfqg->rb_node, st);
Vivek Goyalf26bd1f2009-12-03 12:59:54 -0500928 cfqg->vdisktime += cfq_scale_slice(charge_sl, cfqg);
Vivek Goyaldae739e2009-12-03 12:59:45 -0500929 __cfq_group_service_tree_add(st, cfqg);
930
931 /* This group is being expired. Save the context */
932 if (time_after(cfqd->workload_expires, jiffies)) {
933 cfqg->saved_workload_slice = cfqd->workload_expires
934 - jiffies;
935 cfqg->saved_workload = cfqd->serving_type;
936 cfqg->saved_serving_prio = cfqd->serving_prio;
937 } else
938 cfqg->saved_workload_slice = 0;
Vivek Goyal2868ef72009-12-03 12:59:48 -0500939
940 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
941 st->min_vdisktime);
Vivek Goyale98ef892010-06-18 10:39:47 -0400942 cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
943 cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -0500944}
945
Vivek Goyal25fb5162009-12-03 12:59:46 -0500946#ifdef CONFIG_CFQ_GROUP_IOSCHED
947static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
948{
949 if (blkg)
950 return container_of(blkg, struct cfq_group, blkg);
951 return NULL;
952}
953
Vivek Goyalf8d461d2009-12-03 12:59:52 -0500954void
955cfq_update_blkio_group_weight(struct blkio_group *blkg, unsigned int weight)
956{
957 cfqg_of_blkg(blkg)->weight = weight;
958}
959
Vivek Goyal25fb5162009-12-03 12:59:46 -0500960static struct cfq_group *
961cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
962{
963 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
964 struct cfq_group *cfqg = NULL;
965 void *key = cfqd;
966 int i, j;
967 struct cfq_rb_root *st;
Vivek Goyal22084192009-12-03 12:59:49 -0500968 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
969 unsigned int major, minor;
Vivek Goyal25fb5162009-12-03 12:59:46 -0500970
Vivek Goyal25fb5162009-12-03 12:59:46 -0500971 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
Ricky Beniteza74b2ad2010-04-05 18:22:17 +0200972 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
973 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
974 cfqg->blkg.dev = MKDEV(major, minor);
975 goto done;
976 }
Vivek Goyal25fb5162009-12-03 12:59:46 -0500977 if (cfqg || !create)
978 goto done;
979
980 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
981 if (!cfqg)
982 goto done;
983
Vivek Goyal25fb5162009-12-03 12:59:46 -0500984 for_each_cfqg_st(cfqg, i, j, st)
985 *st = CFQ_RB_ROOT;
986 RB_CLEAR_NODE(&cfqg->rb_node);
987
Vivek Goyalb1c35762009-12-03 12:59:47 -0500988 /*
989 * Take the initial reference that will be released on destroy
990 * This can be thought of a joint reference by cgroup and
991 * elevator which will be dropped by either elevator exit
992 * or cgroup deletion path depending on who is exiting first.
993 */
994 atomic_set(&cfqg->ref, 1);
995
Vivek Goyal25fb5162009-12-03 12:59:46 -0500996 /* Add group onto cgroup list */
Vivek Goyal22084192009-12-03 12:59:49 -0500997 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
Vivek Goyale98ef892010-06-18 10:39:47 -0400998 cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
Vivek Goyal22084192009-12-03 12:59:49 -0500999 MKDEV(major, minor));
Gui Jianfeng34d0f172010-04-13 16:05:49 +08001000 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
Vivek Goyal25fb5162009-12-03 12:59:46 -05001001
1002 /* Add group on cfqd list */
1003 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
1004
1005done:
Vivek Goyal25fb5162009-12-03 12:59:46 -05001006 return cfqg;
1007}
1008
1009/*
1010 * Search for the cfq group current task belongs to. If create = 1, then also
1011 * create the cfq group if it does not exist. request_queue lock must be held.
1012 */
1013static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1014{
1015 struct cgroup *cgroup;
1016 struct cfq_group *cfqg = NULL;
1017
1018 rcu_read_lock();
1019 cgroup = task_cgroup(current, blkio_subsys_id);
1020 cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
1021 if (!cfqg && create)
1022 cfqg = &cfqd->root_group;
1023 rcu_read_unlock();
1024 return cfqg;
1025}
1026
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02001027static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1028{
1029 atomic_inc(&cfqg->ref);
1030 return cfqg;
1031}
1032
Vivek Goyal25fb5162009-12-03 12:59:46 -05001033static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1034{
1035 /* Currently, all async queues are mapped to root group */
1036 if (!cfq_cfqq_sync(cfqq))
1037 cfqg = &cfqq->cfqd->root_group;
1038
1039 cfqq->cfqg = cfqg;
Vivek Goyalb1c35762009-12-03 12:59:47 -05001040 /* cfqq reference on cfqg */
1041 atomic_inc(&cfqq->cfqg->ref);
Vivek Goyal25fb5162009-12-03 12:59:46 -05001042}
Vivek Goyalb1c35762009-12-03 12:59:47 -05001043
1044static void cfq_put_cfqg(struct cfq_group *cfqg)
1045{
1046 struct cfq_rb_root *st;
1047 int i, j;
1048
1049 BUG_ON(atomic_read(&cfqg->ref) <= 0);
1050 if (!atomic_dec_and_test(&cfqg->ref))
1051 return;
1052 for_each_cfqg_st(cfqg, i, j, st)
1053 BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL);
1054 kfree(cfqg);
1055}
1056
1057static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1058{
1059 /* Something wrong if we are trying to remove same group twice */
1060 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1061
1062 hlist_del_init(&cfqg->cfqd_node);
1063
1064 /*
1065 * Put the reference taken at the time of creation so that when all
1066 * queues are gone, group can be destroyed.
1067 */
1068 cfq_put_cfqg(cfqg);
1069}
1070
1071static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1072{
1073 struct hlist_node *pos, *n;
1074 struct cfq_group *cfqg;
1075
1076 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1077 /*
1078 * If cgroup removal path got to blk_group first and removed
1079 * it from cgroup list, then it will take care of destroying
1080 * cfqg also.
1081 */
Vivek Goyale98ef892010-06-18 10:39:47 -04001082 if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
Vivek Goyalb1c35762009-12-03 12:59:47 -05001083 cfq_destroy_cfqg(cfqd, cfqg);
1084 }
1085}
1086
1087/*
1088 * Blk cgroup controller notification saying that blkio_group object is being
1089 * delinked as associated cgroup object is going away. That also means that
1090 * no new IO will come in this group. So get rid of this group as soon as
1091 * any pending IO in the group is finished.
1092 *
1093 * This function is called under rcu_read_lock(). key is the rcu protected
1094 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1095 * read lock.
1096 *
1097 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1098 * it should not be NULL as even if elevator was exiting, cgroup deltion
1099 * path got to it first.
1100 */
1101void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1102{
1103 unsigned long flags;
1104 struct cfq_data *cfqd = key;
1105
1106 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1107 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1108 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1109}
1110
Vivek Goyal25fb5162009-12-03 12:59:46 -05001111#else /* GROUP_IOSCHED */
1112static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1113{
1114 return &cfqd->root_group;
1115}
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02001116
1117static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1118{
Dmitry Monakhov50eaeb32010-04-28 19:50:33 +02001119 return cfqg;
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02001120}
1121
Vivek Goyal25fb5162009-12-03 12:59:46 -05001122static inline void
1123cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1124 cfqq->cfqg = cfqg;
1125}
1126
Vivek Goyalb1c35762009-12-03 12:59:47 -05001127static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1128static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1129
Vivek Goyal25fb5162009-12-03 12:59:46 -05001130#endif /* GROUP_IOSCHED */
1131
Jens Axboe498d3aa2007-04-26 12:54:48 +02001132/*
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001133 * The cfqd->service_trees holds all pending cfq_queue's that have
Jens Axboe498d3aa2007-04-26 12:54:48 +02001134 * requests waiting to be processed. It is sorted in the order that
1135 * we will service the queues.
1136 */
Jens Axboea36e71f2009-04-15 12:15:11 +02001137static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Jens Axboea6151c32009-10-07 20:02:57 +02001138 bool add_front)
Jens Axboed9e76202007-04-20 14:27:50 +02001139{
Jens Axboe08717142008-01-28 11:38:15 +01001140 struct rb_node **p, *parent;
1141 struct cfq_queue *__cfqq;
Jens Axboed9e76202007-04-20 14:27:50 +02001142 unsigned long rb_key;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001143 struct cfq_rb_root *service_tree;
Jens Axboe498d3aa2007-04-26 12:54:48 +02001144 int left;
Vivek Goyaldae739e2009-12-03 12:59:45 -05001145 int new_cfqq = 1;
Vivek Goyalae30c282009-12-03 12:59:55 -05001146 int group_changed = 0;
1147
1148#ifdef CONFIG_CFQ_GROUP_IOSCHED
1149 if (!cfqd->cfq_group_isolation
1150 && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD
1151 && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) {
1152 /* Move this cfq to root group */
1153 cfq_log_cfqq(cfqd, cfqq, "moving to root group");
1154 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1155 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1156 cfqq->orig_cfqg = cfqq->cfqg;
1157 cfqq->cfqg = &cfqd->root_group;
1158 atomic_inc(&cfqd->root_group.ref);
1159 group_changed = 1;
1160 } else if (!cfqd->cfq_group_isolation
1161 && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) {
1162 /* cfqq is sequential now needs to go to its original group */
1163 BUG_ON(cfqq->cfqg != &cfqd->root_group);
1164 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1165 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1166 cfq_put_cfqg(cfqq->cfqg);
1167 cfqq->cfqg = cfqq->orig_cfqg;
1168 cfqq->orig_cfqg = NULL;
1169 group_changed = 1;
1170 cfq_log_cfqq(cfqd, cfqq, "moved to origin group");
1171 }
1172#endif
Jens Axboed9e76202007-04-20 14:27:50 +02001173
Vivek Goyalcdb16e82009-12-03 12:59:38 -05001174 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
Vivek Goyal65b32a52009-12-16 17:52:59 -05001175 cfqq_type(cfqq));
Jens Axboe08717142008-01-28 11:38:15 +01001176 if (cfq_class_idle(cfqq)) {
1177 rb_key = CFQ_IDLE_DELAY;
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001178 parent = rb_last(&service_tree->rb);
Jens Axboe08717142008-01-28 11:38:15 +01001179 if (parent && parent != &cfqq->rb_node) {
1180 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1181 rb_key += __cfqq->rb_key;
1182 } else
1183 rb_key += jiffies;
1184 } else if (!add_front) {
Jens Axboeb9c89462009-10-06 20:53:44 +02001185 /*
1186 * Get our rb key offset. Subtract any residual slice
1187 * value carried from last service. A negative resid
1188 * count indicates slice overrun, and this should position
1189 * the next service time further away in the tree.
1190 */
Jens Axboeedd75ff2007-04-19 12:03:34 +02001191 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
Jens Axboeb9c89462009-10-06 20:53:44 +02001192 rb_key -= cfqq->slice_resid;
Jens Axboeedd75ff2007-04-19 12:03:34 +02001193 cfqq->slice_resid = 0;
Corrado Zoccolo48e025e2009-10-05 08:49:23 +02001194 } else {
1195 rb_key = -HZ;
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001196 __cfqq = cfq_rb_first(service_tree);
Corrado Zoccolo48e025e2009-10-05 08:49:23 +02001197 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1198 }
Jens Axboed9e76202007-04-20 14:27:50 +02001199
1200 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
Vivek Goyaldae739e2009-12-03 12:59:45 -05001201 new_cfqq = 0;
Jens Axboe99f96282007-02-05 11:56:25 +01001202 /*
Jens Axboed9e76202007-04-20 14:27:50 +02001203 * same position, nothing more to do
Jens Axboe99f96282007-02-05 11:56:25 +01001204 */
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001205 if (rb_key == cfqq->rb_key &&
1206 cfqq->service_tree == service_tree)
Jens Axboed9e76202007-04-20 14:27:50 +02001207 return;
Jens Axboe53b03742006-07-28 09:48:51 +02001208
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001209 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1210 cfqq->service_tree = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +02001211 }
Jens Axboed9e76202007-04-20 14:27:50 +02001212
Jens Axboe498d3aa2007-04-26 12:54:48 +02001213 left = 1;
Jens Axboe08717142008-01-28 11:38:15 +01001214 parent = NULL;
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001215 cfqq->service_tree = service_tree;
1216 p = &service_tree->rb.rb_node;
Jens Axboed9e76202007-04-20 14:27:50 +02001217 while (*p) {
Jens Axboe67060e32007-04-18 20:13:32 +02001218 struct rb_node **n;
Jens Axboecc09e292007-04-26 12:53:50 +02001219
Jens Axboed9e76202007-04-20 14:27:50 +02001220 parent = *p;
1221 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1222
Jens Axboe0c534e02007-04-18 20:01:57 +02001223 /*
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001224 * sort by key, that represents service time.
Jens Axboe0c534e02007-04-18 20:01:57 +02001225 */
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001226 if (time_before(rb_key, __cfqq->rb_key))
Jens Axboe67060e32007-04-18 20:13:32 +02001227 n = &(*p)->rb_left;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001228 else {
Jens Axboe67060e32007-04-18 20:13:32 +02001229 n = &(*p)->rb_right;
Jens Axboecc09e292007-04-26 12:53:50 +02001230 left = 0;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001231 }
Jens Axboe67060e32007-04-18 20:13:32 +02001232
1233 p = n;
Jens Axboed9e76202007-04-20 14:27:50 +02001234 }
1235
Jens Axboecc09e292007-04-26 12:53:50 +02001236 if (left)
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001237 service_tree->left = &cfqq->rb_node;
Jens Axboecc09e292007-04-26 12:53:50 +02001238
Jens Axboed9e76202007-04-20 14:27:50 +02001239 cfqq->rb_key = rb_key;
1240 rb_link_node(&cfqq->rb_node, parent, p);
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001241 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1242 service_tree->count++;
Vivek Goyalae30c282009-12-03 12:59:55 -05001243 if ((add_front || !new_cfqq) && !group_changed)
Vivek Goyaldae739e2009-12-03 12:59:45 -05001244 return;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05001245 cfq_group_service_tree_add(cfqd, cfqq->cfqg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246}
1247
Jens Axboea36e71f2009-04-15 12:15:11 +02001248static struct cfq_queue *
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001249cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1250 sector_t sector, struct rb_node **ret_parent,
1251 struct rb_node ***rb_link)
Jens Axboea36e71f2009-04-15 12:15:11 +02001252{
Jens Axboea36e71f2009-04-15 12:15:11 +02001253 struct rb_node **p, *parent;
1254 struct cfq_queue *cfqq = NULL;
1255
1256 parent = NULL;
1257 p = &root->rb_node;
1258 while (*p) {
1259 struct rb_node **n;
1260
1261 parent = *p;
1262 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1263
1264 /*
1265 * Sort strictly based on sector. Smallest to the left,
1266 * largest to the right.
1267 */
Tejun Heo2e46e8b2009-05-07 22:24:41 +09001268 if (sector > blk_rq_pos(cfqq->next_rq))
Jens Axboea36e71f2009-04-15 12:15:11 +02001269 n = &(*p)->rb_right;
Tejun Heo2e46e8b2009-05-07 22:24:41 +09001270 else if (sector < blk_rq_pos(cfqq->next_rq))
Jens Axboea36e71f2009-04-15 12:15:11 +02001271 n = &(*p)->rb_left;
1272 else
1273 break;
1274 p = n;
Jens Axboe3ac6c9f2009-04-23 12:14:56 +02001275 cfqq = NULL;
Jens Axboea36e71f2009-04-15 12:15:11 +02001276 }
1277
1278 *ret_parent = parent;
1279 if (rb_link)
1280 *rb_link = p;
Jens Axboe3ac6c9f2009-04-23 12:14:56 +02001281 return cfqq;
Jens Axboea36e71f2009-04-15 12:15:11 +02001282}
1283
1284static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1285{
Jens Axboea36e71f2009-04-15 12:15:11 +02001286 struct rb_node **p, *parent;
1287 struct cfq_queue *__cfqq;
1288
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001289 if (cfqq->p_root) {
1290 rb_erase(&cfqq->p_node, cfqq->p_root);
1291 cfqq->p_root = NULL;
1292 }
Jens Axboea36e71f2009-04-15 12:15:11 +02001293
1294 if (cfq_class_idle(cfqq))
1295 return;
1296 if (!cfqq->next_rq)
1297 return;
1298
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001299 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
Tejun Heo2e46e8b2009-05-07 22:24:41 +09001300 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1301 blk_rq_pos(cfqq->next_rq), &parent, &p);
Jens Axboe3ac6c9f2009-04-23 12:14:56 +02001302 if (!__cfqq) {
1303 rb_link_node(&cfqq->p_node, parent, p);
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001304 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1305 } else
1306 cfqq->p_root = NULL;
Jens Axboea36e71f2009-04-15 12:15:11 +02001307}
1308
Jens Axboe498d3aa2007-04-26 12:54:48 +02001309/*
1310 * Update cfqq's position in the service tree.
1311 */
Jens Axboeedd75ff2007-04-19 12:03:34 +02001312static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Jens Axboe6d048f52007-04-25 12:44:27 +02001313{
Jens Axboe6d048f52007-04-25 12:44:27 +02001314 /*
1315 * Resorting requires the cfqq to be on the RR list already.
1316 */
Jens Axboea36e71f2009-04-15 12:15:11 +02001317 if (cfq_cfqq_on_rr(cfqq)) {
Jens Axboeedd75ff2007-04-19 12:03:34 +02001318 cfq_service_tree_add(cfqd, cfqq, 0);
Jens Axboea36e71f2009-04-15 12:15:11 +02001319 cfq_prio_tree_add(cfqd, cfqq);
1320 }
Jens Axboe6d048f52007-04-25 12:44:27 +02001321}
1322
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323/*
1324 * add to busy list of queues for service, trying to be fair in ordering
Jens Axboe22e2c502005-06-27 10:55:12 +02001325 * the pending list according to last request service
Linus Torvalds1da177e2005-04-16 15:20:36 -07001326 */
Jens Axboefebffd62008-01-28 13:19:43 +01001327static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328{
Jens Axboe7b679132008-05-30 12:23:07 +02001329 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
Jens Axboe3b181522005-06-27 10:56:24 +02001330 BUG_ON(cfq_cfqq_on_rr(cfqq));
1331 cfq_mark_cfqq_on_rr(cfqq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332 cfqd->busy_queues++;
1333
Jens Axboeedd75ff2007-04-19 12:03:34 +02001334 cfq_resort_rr_list(cfqd, cfqq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335}
1336
Jens Axboe498d3aa2007-04-26 12:54:48 +02001337/*
1338 * Called when the cfqq no longer has requests pending, remove it from
1339 * the service tree.
1340 */
Jens Axboefebffd62008-01-28 13:19:43 +01001341static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342{
Jens Axboe7b679132008-05-30 12:23:07 +02001343 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
Jens Axboe3b181522005-06-27 10:56:24 +02001344 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1345 cfq_clear_cfqq_on_rr(cfqq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01001347 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1348 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1349 cfqq->service_tree = NULL;
1350 }
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001351 if (cfqq->p_root) {
1352 rb_erase(&cfqq->p_node, cfqq->p_root);
1353 cfqq->p_root = NULL;
1354 }
Jens Axboed9e76202007-04-20 14:27:50 +02001355
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05001356 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 BUG_ON(!cfqd->busy_queues);
1358 cfqd->busy_queues--;
1359}
1360
1361/*
1362 * rb tree support functions
1363 */
Jens Axboefebffd62008-01-28 13:19:43 +01001364static void cfq_del_rq_rb(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365{
Jens Axboe5e705372006-07-13 12:39:25 +02001366 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe5e705372006-07-13 12:39:25 +02001367 const int sync = rq_is_sync(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368
Jens Axboeb4878f22005-10-20 16:42:29 +02001369 BUG_ON(!cfqq->queued[sync]);
1370 cfqq->queued[sync]--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371
Jens Axboe5e705372006-07-13 12:39:25 +02001372 elv_rb_del(&cfqq->sort_list, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373
Vivek Goyalf04a6422009-12-03 12:59:40 -05001374 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1375 /*
1376 * Queue will be deleted from service tree when we actually
1377 * expire it later. Right now just remove it from prio tree
1378 * as it is empty.
1379 */
1380 if (cfqq->p_root) {
1381 rb_erase(&cfqq->p_node, cfqq->p_root);
1382 cfqq->p_root = NULL;
1383 }
1384 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385}
1386
Jens Axboe5e705372006-07-13 12:39:25 +02001387static void cfq_add_rq_rb(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388{
Jens Axboe5e705372006-07-13 12:39:25 +02001389 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390 struct cfq_data *cfqd = cfqq->cfqd;
Jens Axboea36e71f2009-04-15 12:15:11 +02001391 struct request *__alias, *prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392
Jens Axboe5380a102006-07-13 12:37:56 +02001393 cfqq->queued[rq_is_sync(rq)]++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394
1395 /*
1396 * looks a little odd, but the first insert might return an alias.
1397 * if that happens, put the alias on the dispatch list
1398 */
Jens Axboe21183b02006-07-13 12:33:14 +02001399 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
Jens Axboe5e705372006-07-13 12:39:25 +02001400 cfq_dispatch_insert(cfqd->queue, __alias);
Jens Axboe5fccbf62006-10-31 14:21:55 +01001401
1402 if (!cfq_cfqq_on_rr(cfqq))
1403 cfq_add_cfqq_rr(cfqd, cfqq);
Jens Axboe5044eed2007-04-25 11:53:48 +02001404
1405 /*
1406 * check if this request is a better next-serve candidate
1407 */
Jens Axboea36e71f2009-04-15 12:15:11 +02001408 prev = cfqq->next_rq;
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +01001409 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
Jens Axboea36e71f2009-04-15 12:15:11 +02001410
1411 /*
1412 * adjust priority tree position, if ->next_rq changes
1413 */
1414 if (prev != cfqq->next_rq)
1415 cfq_prio_tree_add(cfqd, cfqq);
1416
Jens Axboe5044eed2007-04-25 11:53:48 +02001417 BUG_ON(!cfqq->next_rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418}
1419
Jens Axboefebffd62008-01-28 13:19:43 +01001420static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421{
Jens Axboe5380a102006-07-13 12:37:56 +02001422 elv_rb_del(&cfqq->sort_list, rq);
1423 cfqq->queued[rq_is_sync(rq)]--;
Vivek Goyale98ef892010-06-18 10:39:47 -04001424 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1425 rq_data_dir(rq), rq_is_sync(rq));
Jens Axboe5e705372006-07-13 12:39:25 +02001426 cfq_add_rq_rb(rq);
Vivek Goyale98ef892010-06-18 10:39:47 -04001427 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02001428 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1429 rq_is_sync(rq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001430}
1431
Jens Axboe206dc692006-03-28 13:03:44 +02001432static struct request *
1433cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434{
Jens Axboe206dc692006-03-28 13:03:44 +02001435 struct task_struct *tsk = current;
Vasily Tarasov91fac312007-04-25 12:29:51 +02001436 struct cfq_io_context *cic;
Jens Axboe206dc692006-03-28 13:03:44 +02001437 struct cfq_queue *cfqq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438
Jens Axboe4ac845a2008-01-24 08:44:49 +01001439 cic = cfq_cic_lookup(cfqd, tsk->io_context);
Vasily Tarasov91fac312007-04-25 12:29:51 +02001440 if (!cic)
1441 return NULL;
1442
1443 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
Jens Axboe89850f72006-07-22 16:48:31 +02001444 if (cfqq) {
1445 sector_t sector = bio->bi_sector + bio_sectors(bio);
1446
Jens Axboe21183b02006-07-13 12:33:14 +02001447 return elv_rb_find(&cfqq->sort_list, sector);
Jens Axboe89850f72006-07-22 16:48:31 +02001448 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450 return NULL;
1451}
1452
Jens Axboe165125e2007-07-24 09:28:11 +02001453static void cfq_activate_request(struct request_queue *q, struct request *rq)
Jens Axboeb4878f22005-10-20 16:42:29 +02001454{
1455 struct cfq_data *cfqd = q->elevator->elevator_data;
1456
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01001457 cfqd->rq_in_driver++;
Jens Axboe7b679132008-05-30 12:23:07 +02001458 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01001459 cfqd->rq_in_driver);
Jens Axboe25776e32006-06-01 10:12:26 +02001460
Tejun Heo5b936292009-05-07 22:24:38 +09001461 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
Jens Axboeb4878f22005-10-20 16:42:29 +02001462}
1463
Jens Axboe165125e2007-07-24 09:28:11 +02001464static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465{
Jens Axboe22e2c502005-06-27 10:55:12 +02001466 struct cfq_data *cfqd = q->elevator->elevator_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01001468 WARN_ON(!cfqd->rq_in_driver);
1469 cfqd->rq_in_driver--;
Jens Axboe7b679132008-05-30 12:23:07 +02001470 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01001471 cfqd->rq_in_driver);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472}
1473
Jens Axboeb4878f22005-10-20 16:42:29 +02001474static void cfq_remove_request(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475{
Jens Axboe5e705372006-07-13 12:39:25 +02001476 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe21183b02006-07-13 12:33:14 +02001477
Jens Axboe5e705372006-07-13 12:39:25 +02001478 if (cfqq->next_rq == rq)
1479 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001480
Jens Axboeb4878f22005-10-20 16:42:29 +02001481 list_del_init(&rq->queuelist);
Jens Axboe5e705372006-07-13 12:39:25 +02001482 cfq_del_rq_rb(rq);
Jens Axboe374f84a2006-07-23 01:42:19 +02001483
Aaron Carroll45333d52008-08-26 15:52:36 +02001484 cfqq->cfqd->rq_queued--;
Vivek Goyale98ef892010-06-18 10:39:47 -04001485 cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
1486 rq_data_dir(rq), rq_is_sync(rq));
Jens Axboe374f84a2006-07-23 01:42:19 +02001487 if (rq_is_meta(rq)) {
1488 WARN_ON(!cfqq->meta_pending);
1489 cfqq->meta_pending--;
1490 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491}
1492
Jens Axboe165125e2007-07-24 09:28:11 +02001493static int cfq_merge(struct request_queue *q, struct request **req,
1494 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495{
1496 struct cfq_data *cfqd = q->elevator->elevator_data;
1497 struct request *__rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498
Jens Axboe206dc692006-03-28 13:03:44 +02001499 __rq = cfq_find_rq_fmerge(cfqd, bio);
Jens Axboe22e2c502005-06-27 10:55:12 +02001500 if (__rq && elv_rq_merge_ok(__rq, bio)) {
Jens Axboe98170642006-07-28 09:23:08 +02001501 *req = __rq;
1502 return ELEVATOR_FRONT_MERGE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503 }
1504
1505 return ELEVATOR_NO_MERGE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001506}
1507
Jens Axboe165125e2007-07-24 09:28:11 +02001508static void cfq_merged_request(struct request_queue *q, struct request *req,
Jens Axboe21183b02006-07-13 12:33:14 +02001509 int type)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001510{
Jens Axboe21183b02006-07-13 12:33:14 +02001511 if (type == ELEVATOR_FRONT_MERGE) {
Jens Axboe5e705372006-07-13 12:39:25 +02001512 struct cfq_queue *cfqq = RQ_CFQQ(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001513
Jens Axboe5e705372006-07-13 12:39:25 +02001514 cfq_reposition_rq_rb(cfqq, req);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516}
1517
Divyesh Shah812d4022010-04-08 21:14:23 -07001518static void cfq_bio_merged(struct request_queue *q, struct request *req,
1519 struct bio *bio)
1520{
Vivek Goyale98ef892010-06-18 10:39:47 -04001521 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
1522 bio_data_dir(bio), cfq_bio_sync(bio));
Divyesh Shah812d4022010-04-08 21:14:23 -07001523}
1524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525static void
Jens Axboe165125e2007-07-24 09:28:11 +02001526cfq_merged_requests(struct request_queue *q, struct request *rq,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 struct request *next)
1528{
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +01001529 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001530 /*
1531 * reposition in fifo if next is older than rq
1532 */
1533 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
Jens Axboe30996f42009-10-05 11:03:39 +02001534 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
Jens Axboe22e2c502005-06-27 10:55:12 +02001535 list_move(&rq->queuelist, &next->queuelist);
Jens Axboe30996f42009-10-05 11:03:39 +02001536 rq_set_fifo_time(rq, rq_fifo_time(next));
1537 }
Jens Axboe22e2c502005-06-27 10:55:12 +02001538
Corrado Zoccolocf7c25c2009-11-08 17:16:46 +01001539 if (cfqq->next_rq == next)
1540 cfqq->next_rq = rq;
Jens Axboeb4878f22005-10-20 16:42:29 +02001541 cfq_remove_request(next);
Vivek Goyale98ef892010-06-18 10:39:47 -04001542 cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
1543 rq_data_dir(next), rq_is_sync(next));
Jens Axboe22e2c502005-06-27 10:55:12 +02001544}
1545
Jens Axboe165125e2007-07-24 09:28:11 +02001546static int cfq_allow_merge(struct request_queue *q, struct request *rq,
Jens Axboeda775262006-12-20 11:04:12 +01001547 struct bio *bio)
1548{
1549 struct cfq_data *cfqd = q->elevator->elevator_data;
Vasily Tarasov91fac312007-04-25 12:29:51 +02001550 struct cfq_io_context *cic;
Jens Axboeda775262006-12-20 11:04:12 +01001551 struct cfq_queue *cfqq;
Jens Axboeda775262006-12-20 11:04:12 +01001552
1553 /*
Jens Axboeec8acb62007-01-02 18:32:11 +01001554 * Disallow merge of a sync bio into an async request.
Jens Axboeda775262006-12-20 11:04:12 +01001555 */
Vasily Tarasov91fac312007-04-25 12:29:51 +02001556 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
Jens Axboea6151c32009-10-07 20:02:57 +02001557 return false;
Jens Axboeda775262006-12-20 11:04:12 +01001558
1559 /*
Jens Axboe719d3402006-12-22 09:38:53 +01001560 * Lookup the cfqq that this bio will be queued with. Allow
1561 * merge only if rq is queued there.
Jens Axboeda775262006-12-20 11:04:12 +01001562 */
Jens Axboe4ac845a2008-01-24 08:44:49 +01001563 cic = cfq_cic_lookup(cfqd, current->io_context);
Vasily Tarasov91fac312007-04-25 12:29:51 +02001564 if (!cic)
Jens Axboea6151c32009-10-07 20:02:57 +02001565 return false;
Jens Axboe719d3402006-12-22 09:38:53 +01001566
Vasily Tarasov91fac312007-04-25 12:29:51 +02001567 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
Jens Axboea6151c32009-10-07 20:02:57 +02001568 return cfqq == RQ_CFQQ(rq);
Jens Axboeda775262006-12-20 11:04:12 +01001569}
1570
Divyesh Shah812df482010-04-08 21:15:35 -07001571static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1572{
1573 del_timer(&cfqd->idle_slice_timer);
Vivek Goyale98ef892010-06-18 10:39:47 -04001574 cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
Divyesh Shah812df482010-04-08 21:15:35 -07001575}
1576
Jens Axboefebffd62008-01-28 13:19:43 +01001577static void __cfq_set_active_queue(struct cfq_data *cfqd,
1578 struct cfq_queue *cfqq)
Jens Axboe22e2c502005-06-27 10:55:12 +02001579{
1580 if (cfqq) {
Divyesh Shahb1ffe732010-03-25 15:45:03 +01001581 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1582 cfqd->serving_prio, cfqd->serving_type);
Vivek Goyale98ef892010-06-18 10:39:47 -04001583 cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
Vivek Goyaldae739e2009-12-03 12:59:45 -05001584 cfqq->slice_start = 0;
1585 cfqq->dispatch_start = jiffies;
Vivek Goyalf75edf22009-12-03 12:59:53 -05001586 cfqq->allocated_slice = 0;
Jens Axboe22e2c502005-06-27 10:55:12 +02001587 cfqq->slice_end = 0;
Jens Axboe2f5cb732009-04-07 08:51:19 +02001588 cfqq->slice_dispatch = 0;
1589
Jens Axboe2f5cb732009-04-07 08:51:19 +02001590 cfq_clear_cfqq_wait_request(cfqq);
Jens Axboeb0291952009-04-07 11:38:31 +02001591 cfq_clear_cfqq_must_dispatch(cfqq);
Jens Axboe3b181522005-06-27 10:56:24 +02001592 cfq_clear_cfqq_must_alloc_slice(cfqq);
1593 cfq_clear_cfqq_fifo_expire(cfqq);
Jens Axboe44f7c162007-01-19 11:51:58 +11001594 cfq_mark_cfqq_slice_new(cfqq);
Jens Axboe2f5cb732009-04-07 08:51:19 +02001595
Divyesh Shah812df482010-04-08 21:15:35 -07001596 cfq_del_timer(cfqd, cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001597 }
1598
1599 cfqd->active_queue = cfqq;
1600}
1601
1602/*
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001603 * current cfqq expired its slice (or was too idle), select new one
1604 */
1605static void
1606__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Vivek Goyale5ff0822010-04-26 19:25:11 +02001607 bool timed_out)
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001608{
Jens Axboe7b679132008-05-30 12:23:07 +02001609 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1610
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001611 if (cfq_cfqq_wait_request(cfqq))
Divyesh Shah812df482010-04-08 21:15:35 -07001612 cfq_del_timer(cfqd, cfqq);
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001613
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001614 cfq_clear_cfqq_wait_request(cfqq);
Vivek Goyalf75edf22009-12-03 12:59:53 -05001615 cfq_clear_cfqq_wait_busy(cfqq);
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001616
1617 /*
Shaohua Liae54abe2010-02-05 13:11:45 +01001618 * If this cfqq is shared between multiple processes, check to
1619 * make sure that those processes are still issuing I/Os within
1620 * the mean seek distance. If not, it may be time to break the
1621 * queues apart again.
1622 */
1623 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1624 cfq_mark_cfqq_split_coop(cfqq);
1625
1626 /*
Jens Axboe6084cdd2007-04-23 08:25:00 +02001627 * store what was left of this slice, if the queue idled/timed out
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001628 */
Jens Axboe7b679132008-05-30 12:23:07 +02001629 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
Jens Axboec5b680f2007-01-19 11:56:49 +11001630 cfqq->slice_resid = cfqq->slice_end - jiffies;
Jens Axboe7b679132008-05-30 12:23:07 +02001631 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1632 }
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001633
Vivek Goyale5ff0822010-04-26 19:25:11 +02001634 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
Vivek Goyaldae739e2009-12-03 12:59:45 -05001635
Vivek Goyalf04a6422009-12-03 12:59:40 -05001636 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1637 cfq_del_cfqq_rr(cfqd, cfqq);
1638
Jens Axboeedd75ff2007-04-19 12:03:34 +02001639 cfq_resort_rr_list(cfqd, cfqq);
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001640
1641 if (cfqq == cfqd->active_queue)
1642 cfqd->active_queue = NULL;
1643
Vivek Goyaldae739e2009-12-03 12:59:45 -05001644 if (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active)
1645 cfqd->grp_service_tree.active = NULL;
1646
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001647 if (cfqd->active_cic) {
1648 put_io_context(cfqd->active_cic->ioc);
1649 cfqd->active_cic = NULL;
1650 }
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001651}
1652
Vivek Goyale5ff0822010-04-26 19:25:11 +02001653static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001654{
1655 struct cfq_queue *cfqq = cfqd->active_queue;
1656
1657 if (cfqq)
Vivek Goyale5ff0822010-04-26 19:25:11 +02001658 __cfq_slice_expired(cfqd, cfqq, timed_out);
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001659}
1660
Jens Axboe498d3aa2007-04-26 12:54:48 +02001661/*
1662 * Get next queue for service. Unless we have a queue preemption,
1663 * we'll simply select the first cfqq in the service tree.
1664 */
Jens Axboe6d048f52007-04-25 12:44:27 +02001665static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
Jens Axboe22e2c502005-06-27 10:55:12 +02001666{
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001667 struct cfq_rb_root *service_tree =
Vivek Goyalcdb16e82009-12-03 12:59:38 -05001668 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
Vivek Goyal65b32a52009-12-16 17:52:59 -05001669 cfqd->serving_type);
Jens Axboeedd75ff2007-04-19 12:03:34 +02001670
Vivek Goyalf04a6422009-12-03 12:59:40 -05001671 if (!cfqd->rq_queued)
1672 return NULL;
1673
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05001674 /* There is nothing to dispatch */
1675 if (!service_tree)
1676 return NULL;
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001677 if (RB_EMPTY_ROOT(&service_tree->rb))
1678 return NULL;
1679 return cfq_rb_first(service_tree);
Jens Axboe6d048f52007-04-25 12:44:27 +02001680}
1681
Vivek Goyalf04a6422009-12-03 12:59:40 -05001682static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1683{
Vivek Goyal25fb5162009-12-03 12:59:46 -05001684 struct cfq_group *cfqg;
Vivek Goyalf04a6422009-12-03 12:59:40 -05001685 struct cfq_queue *cfqq;
1686 int i, j;
1687 struct cfq_rb_root *st;
1688
1689 if (!cfqd->rq_queued)
1690 return NULL;
1691
Vivek Goyal25fb5162009-12-03 12:59:46 -05001692 cfqg = cfq_get_next_cfqg(cfqd);
1693 if (!cfqg)
1694 return NULL;
1695
Vivek Goyalf04a6422009-12-03 12:59:40 -05001696 for_each_cfqg_st(cfqg, i, j, st)
1697 if ((cfqq = cfq_rb_first(st)) != NULL)
1698 return cfqq;
1699 return NULL;
1700}
1701
Jens Axboe498d3aa2007-04-26 12:54:48 +02001702/*
1703 * Get and set a new active queue for service.
1704 */
Jens Axboea36e71f2009-04-15 12:15:11 +02001705static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1706 struct cfq_queue *cfqq)
Jens Axboe6d048f52007-04-25 12:44:27 +02001707{
Jens Axboee00ef792009-11-04 08:54:55 +01001708 if (!cfqq)
Jens Axboea36e71f2009-04-15 12:15:11 +02001709 cfqq = cfq_get_next_queue(cfqd);
Jens Axboe6d048f52007-04-25 12:44:27 +02001710
Jens Axboe22e2c502005-06-27 10:55:12 +02001711 __cfq_set_active_queue(cfqd, cfqq);
Jens Axboe3b181522005-06-27 10:56:24 +02001712 return cfqq;
Jens Axboe22e2c502005-06-27 10:55:12 +02001713}
1714
Jens Axboed9e76202007-04-20 14:27:50 +02001715static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1716 struct request *rq)
1717{
Tejun Heo83096eb2009-05-07 22:24:39 +09001718 if (blk_rq_pos(rq) >= cfqd->last_position)
1719 return blk_rq_pos(rq) - cfqd->last_position;
Jens Axboed9e76202007-04-20 14:27:50 +02001720 else
Tejun Heo83096eb2009-05-07 22:24:39 +09001721 return cfqd->last_position - blk_rq_pos(rq);
Jens Axboed9e76202007-04-20 14:27:50 +02001722}
1723
Jeff Moyerb2c18e12009-10-23 17:14:49 -04001724static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Shaohua Lie9ce3352010-03-19 08:03:04 +01001725 struct request *rq)
Jens Axboe6d048f52007-04-25 12:44:27 +02001726{
Shaohua Lie9ce3352010-03-19 08:03:04 +01001727 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
Jens Axboe6d048f52007-04-25 12:44:27 +02001728}
1729
Jens Axboea36e71f2009-04-15 12:15:11 +02001730static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1731 struct cfq_queue *cur_cfqq)
Jens Axboe6d048f52007-04-25 12:44:27 +02001732{
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001733 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
Jens Axboea36e71f2009-04-15 12:15:11 +02001734 struct rb_node *parent, *node;
1735 struct cfq_queue *__cfqq;
1736 sector_t sector = cfqd->last_position;
1737
1738 if (RB_EMPTY_ROOT(root))
1739 return NULL;
1740
1741 /*
1742 * First, if we find a request starting at the end of the last
1743 * request, choose it.
1744 */
Jens Axboef2d1f0a2009-04-23 12:19:38 +02001745 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
Jens Axboea36e71f2009-04-15 12:15:11 +02001746 if (__cfqq)
1747 return __cfqq;
1748
1749 /*
1750 * If the exact sector wasn't found, the parent of the NULL leaf
1751 * will contain the closest sector.
1752 */
1753 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
Shaohua Lie9ce3352010-03-19 08:03:04 +01001754 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
Jens Axboea36e71f2009-04-15 12:15:11 +02001755 return __cfqq;
1756
Tejun Heo2e46e8b2009-05-07 22:24:41 +09001757 if (blk_rq_pos(__cfqq->next_rq) < sector)
Jens Axboea36e71f2009-04-15 12:15:11 +02001758 node = rb_next(&__cfqq->p_node);
1759 else
1760 node = rb_prev(&__cfqq->p_node);
1761 if (!node)
1762 return NULL;
1763
1764 __cfqq = rb_entry(node, struct cfq_queue, p_node);
Shaohua Lie9ce3352010-03-19 08:03:04 +01001765 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
Jens Axboea36e71f2009-04-15 12:15:11 +02001766 return __cfqq;
1767
1768 return NULL;
1769}
1770
1771/*
1772 * cfqd - obvious
1773 * cur_cfqq - passed in so that we don't decide that the current queue is
1774 * closely cooperating with itself.
1775 *
1776 * So, basically we're assuming that that cur_cfqq has dispatched at least
1777 * one request, and that cfqd->last_position reflects a position on the disk
1778 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1779 * assumption.
1780 */
1781static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
Jeff Moyerb3b6d042009-10-23 17:14:51 -04001782 struct cfq_queue *cur_cfqq)
Jens Axboea36e71f2009-04-15 12:15:11 +02001783{
1784 struct cfq_queue *cfqq;
1785
Divyesh Shah39c01b22010-03-25 15:45:57 +01001786 if (cfq_class_idle(cur_cfqq))
1787 return NULL;
Jeff Moyere6c5bc72009-10-23 17:14:52 -04001788 if (!cfq_cfqq_sync(cur_cfqq))
1789 return NULL;
1790 if (CFQQ_SEEKY(cur_cfqq))
1791 return NULL;
1792
Jens Axboea36e71f2009-04-15 12:15:11 +02001793 /*
Gui Jianfengb9d8f4c2009-12-08 08:54:17 +01001794 * Don't search priority tree if it's the only queue in the group.
1795 */
1796 if (cur_cfqq->cfqg->nr_cfqq == 1)
1797 return NULL;
1798
1799 /*
Jens Axboed9e76202007-04-20 14:27:50 +02001800 * We should notice if some of the queues are cooperating, eg
1801 * working closely on the same area of the disk. In that case,
1802 * we can group them together and don't waste time idling.
Jens Axboe6d048f52007-04-25 12:44:27 +02001803 */
Jens Axboea36e71f2009-04-15 12:15:11 +02001804 cfqq = cfqq_close(cfqd, cur_cfqq);
1805 if (!cfqq)
1806 return NULL;
1807
Vivek Goyal8682e1f2009-12-03 12:59:50 -05001808 /* If new queue belongs to different cfq_group, don't choose it */
1809 if (cur_cfqq->cfqg != cfqq->cfqg)
1810 return NULL;
1811
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04001812 /*
1813 * It only makes sense to merge sync queues.
1814 */
1815 if (!cfq_cfqq_sync(cfqq))
1816 return NULL;
Jeff Moyere6c5bc72009-10-23 17:14:52 -04001817 if (CFQQ_SEEKY(cfqq))
1818 return NULL;
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04001819
Corrado Zoccoloc0324a02009-10-27 19:16:03 +01001820 /*
1821 * Do not merge queues of different priority classes
1822 */
1823 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1824 return NULL;
1825
Jens Axboea36e71f2009-04-15 12:15:11 +02001826 return cfqq;
Jens Axboe6d048f52007-04-25 12:44:27 +02001827}
1828
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01001829/*
1830 * Determine whether we should enforce idle window for this queue.
1831 */
1832
1833static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1834{
1835 enum wl_prio_t prio = cfqq_prio(cfqq);
Corrado Zoccolo718eee02009-10-26 22:45:29 +01001836 struct cfq_rb_root *service_tree = cfqq->service_tree;
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01001837
Vivek Goyalf04a6422009-12-03 12:59:40 -05001838 BUG_ON(!service_tree);
1839 BUG_ON(!service_tree->count);
1840
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01001841 /* We never do for idle class queues. */
1842 if (prio == IDLE_WORKLOAD)
1843 return false;
1844
1845 /* We do for queues that were marked with idle window flag. */
Shaohua Li3c764b72009-12-04 13:12:06 +01001846 if (cfq_cfqq_idle_window(cfqq) &&
1847 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01001848 return true;
1849
1850 /*
1851 * Otherwise, we do only if they are the last ones
1852 * in their service tree.
1853 */
Divyesh Shahb1ffe732010-03-25 15:45:03 +01001854 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
1855 return 1;
1856 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1857 service_tree->count);
1858 return 0;
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01001859}
1860
Jens Axboe6d048f52007-04-25 12:44:27 +02001861static void cfq_arm_slice_timer(struct cfq_data *cfqd)
Jens Axboe22e2c502005-06-27 10:55:12 +02001862{
Jens Axboe17926692007-01-19 11:59:30 +11001863 struct cfq_queue *cfqq = cfqd->active_queue;
Jens Axboe206dc692006-03-28 13:03:44 +02001864 struct cfq_io_context *cic;
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001865 unsigned long sl;
1866
Jens Axboea68bbdd2008-09-24 13:03:33 +02001867 /*
Jens Axboef7d7b7a2008-09-25 11:37:50 +02001868 * SSD device without seek penalty, disable idling. But only do so
1869 * for devices that support queuing, otherwise we still have a problem
1870 * with sync vs async workloads.
Jens Axboea68bbdd2008-09-24 13:03:33 +02001871 */
Jens Axboef7d7b7a2008-09-25 11:37:50 +02001872 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
Jens Axboea68bbdd2008-09-24 13:03:33 +02001873 return;
1874
Jens Axboedd67d052006-06-21 09:36:18 +02001875 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
Jens Axboe6d048f52007-04-25 12:44:27 +02001876 WARN_ON(cfq_cfqq_slice_new(cfqq));
Jens Axboe22e2c502005-06-27 10:55:12 +02001877
1878 /*
1879 * idle is disabled, either manually or by past process history
1880 */
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01001881 if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
Jens Axboe6d048f52007-04-25 12:44:27 +02001882 return;
1883
Jens Axboe22e2c502005-06-27 10:55:12 +02001884 /*
Corrado Zoccolo8e550632009-11-26 10:02:58 +01001885 * still active requests from this queue, don't idle
Jens Axboe7b679132008-05-30 12:23:07 +02001886 */
Corrado Zoccolo8e550632009-11-26 10:02:58 +01001887 if (cfqq->dispatched)
Jens Axboe7b679132008-05-30 12:23:07 +02001888 return;
1889
1890 /*
Jens Axboe22e2c502005-06-27 10:55:12 +02001891 * task has exited, don't wait
1892 */
Jens Axboe206dc692006-03-28 13:03:44 +02001893 cic = cfqd->active_cic;
Nikanth Karthikesan66dac982007-11-27 12:47:04 +01001894 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
Jens Axboe6d048f52007-04-25 12:44:27 +02001895 return;
1896
Corrado Zoccolo355b6592009-10-08 08:43:32 +02001897 /*
1898 * If our average think time is larger than the remaining time
1899 * slice, then don't idle. This avoids overrunning the allotted
1900 * time slice.
1901 */
1902 if (sample_valid(cic->ttime_samples) &&
Divyesh Shahb1ffe732010-03-25 15:45:03 +01001903 (cfqq->slice_end - jiffies < cic->ttime_mean)) {
1904 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
1905 cic->ttime_mean);
Corrado Zoccolo355b6592009-10-08 08:43:32 +02001906 return;
Divyesh Shahb1ffe732010-03-25 15:45:03 +01001907 }
Corrado Zoccolo355b6592009-10-08 08:43:32 +02001908
Jens Axboe3b181522005-06-27 10:56:24 +02001909 cfq_mark_cfqq_wait_request(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001910
Jens Axboe6d048f52007-04-25 12:44:27 +02001911 sl = cfqd->cfq_slice_idle;
Jens Axboe206dc692006-03-28 13:03:44 +02001912
Jens Axboe7b14e3b2006-02-28 09:35:11 +01001913 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
Vivek Goyale98ef892010-06-18 10:39:47 -04001914 cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
Jens Axboe9481ffd2009-04-15 12:14:13 +02001915 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001916}
1917
Jens Axboe498d3aa2007-04-26 12:54:48 +02001918/*
1919 * Move request from internal lists to the request queue dispatch list.
1920 */
Jens Axboe165125e2007-07-24 09:28:11 +02001921static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001922{
Jens Axboe3ed9a292007-04-23 08:33:33 +02001923 struct cfq_data *cfqd = q->elevator->elevator_data;
Jens Axboe5e705372006-07-13 12:39:25 +02001924 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02001925
Jens Axboe7b679132008-05-30 12:23:07 +02001926 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1927
Jeff Moyer06d21882009-09-11 17:08:59 +02001928 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
Jens Axboe5380a102006-07-13 12:37:56 +02001929 cfq_remove_request(rq);
Jens Axboe6d048f52007-04-25 12:44:27 +02001930 cfqq->dispatched++;
Jens Axboe5380a102006-07-13 12:37:56 +02001931 elv_dispatch_sort(q, rq);
Jens Axboe3ed9a292007-04-23 08:33:33 +02001932
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01001933 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
Vivek Goyale98ef892010-06-18 10:39:47 -04001934 cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
Divyesh Shah84c124d2010-04-09 08:31:19 +02001935 rq_data_dir(rq), rq_is_sync(rq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936}
1937
1938/*
1939 * return expired entry, or NULL to just start from scratch in rbtree
1940 */
Jens Axboefebffd62008-01-28 13:19:43 +01001941static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942{
Jens Axboe30996f42009-10-05 11:03:39 +02001943 struct request *rq = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001944
Jens Axboe3b181522005-06-27 10:56:24 +02001945 if (cfq_cfqq_fifo_expire(cfqq))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946 return NULL;
Jens Axboecb887412007-01-19 12:01:16 +11001947
1948 cfq_mark_cfqq_fifo_expire(cfqq);
1949
Jens Axboe89850f72006-07-22 16:48:31 +02001950 if (list_empty(&cfqq->fifo))
1951 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001952
Jens Axboe89850f72006-07-22 16:48:31 +02001953 rq = rq_entry_fifo(cfqq->fifo.next);
Jens Axboe30996f42009-10-05 11:03:39 +02001954 if (time_before(jiffies, rq_fifo_time(rq)))
Jens Axboe7b679132008-05-30 12:23:07 +02001955 rq = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001956
Jens Axboe30996f42009-10-05 11:03:39 +02001957 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
Jens Axboe6d048f52007-04-25 12:44:27 +02001958 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001959}
1960
Jens Axboe22e2c502005-06-27 10:55:12 +02001961static inline int
1962cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1963{
1964 const int base_rq = cfqd->cfq_slice_async_rq;
1965
1966 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1967
1968 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1969}
1970
1971/*
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04001972 * Must be called with the queue_lock held.
1973 */
1974static int cfqq_process_refs(struct cfq_queue *cfqq)
1975{
1976 int process_refs, io_refs;
1977
1978 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
1979 process_refs = atomic_read(&cfqq->ref) - io_refs;
1980 BUG_ON(process_refs < 0);
1981 return process_refs;
1982}
1983
1984static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
1985{
Jeff Moyere6c5bc72009-10-23 17:14:52 -04001986 int process_refs, new_process_refs;
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04001987 struct cfq_queue *__cfqq;
1988
Jeff Moyerc10b61f2010-06-17 10:19:11 -04001989 /*
1990 * If there are no process references on the new_cfqq, then it is
1991 * unsafe to follow the ->new_cfqq chain as other cfqq's in the
1992 * chain may have dropped their last reference (not just their
1993 * last process reference).
1994 */
1995 if (!cfqq_process_refs(new_cfqq))
1996 return;
1997
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04001998 /* Avoid a circular list and skip interim queue merges */
1999 while ((__cfqq = new_cfqq->new_cfqq)) {
2000 if (__cfqq == cfqq)
2001 return;
2002 new_cfqq = __cfqq;
2003 }
2004
2005 process_refs = cfqq_process_refs(cfqq);
Jeff Moyerc10b61f2010-06-17 10:19:11 -04002006 new_process_refs = cfqq_process_refs(new_cfqq);
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002007 /*
2008 * If the process for the cfqq has gone away, there is no
2009 * sense in merging the queues.
2010 */
Jeff Moyerc10b61f2010-06-17 10:19:11 -04002011 if (process_refs == 0 || new_process_refs == 0)
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002012 return;
2013
Jeff Moyere6c5bc72009-10-23 17:14:52 -04002014 /*
2015 * Merge in the direction of the lesser amount of work.
2016 */
Jeff Moyere6c5bc72009-10-23 17:14:52 -04002017 if (new_process_refs >= process_refs) {
2018 cfqq->new_cfqq = new_cfqq;
2019 atomic_add(process_refs, &new_cfqq->ref);
2020 } else {
2021 new_cfqq->new_cfqq = cfqq;
2022 atomic_add(new_process_refs, &cfqq->ref);
2023 }
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002024}
2025
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002026static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
Vivek Goyal65b32a52009-12-16 17:52:59 -05002027 struct cfq_group *cfqg, enum wl_prio_t prio)
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002028{
2029 struct cfq_queue *queue;
2030 int i;
2031 bool key_valid = false;
2032 unsigned long lowest_key = 0;
2033 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2034
Vivek Goyal65b32a52009-12-16 17:52:59 -05002035 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2036 /* select the one with lowest rb_key */
2037 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002038 if (queue &&
2039 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2040 lowest_key = queue->rb_key;
2041 cur_best = i;
2042 key_valid = true;
2043 }
2044 }
2045
2046 return cur_best;
2047}
2048
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002049static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002050{
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002051 unsigned slice;
2052 unsigned count;
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002053 struct cfq_rb_root *st;
Vivek Goyal58ff82f2009-12-03 12:59:44 -05002054 unsigned group_slice;
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002055
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002056 if (!cfqg) {
2057 cfqd->serving_prio = IDLE_WORKLOAD;
2058 cfqd->workload_expires = jiffies + 1;
2059 return;
2060 }
2061
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002062 /* Choose next priority. RT > BE > IDLE */
Vivek Goyal58ff82f2009-12-03 12:59:44 -05002063 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002064 cfqd->serving_prio = RT_WORKLOAD;
Vivek Goyal58ff82f2009-12-03 12:59:44 -05002065 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002066 cfqd->serving_prio = BE_WORKLOAD;
2067 else {
2068 cfqd->serving_prio = IDLE_WORKLOAD;
2069 cfqd->workload_expires = jiffies + 1;
2070 return;
2071 }
2072
2073 /*
2074 * For RT and BE, we have to choose also the type
2075 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2076 * expiration time
2077 */
Vivek Goyal65b32a52009-12-16 17:52:59 -05002078 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002079 count = st->count;
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002080
2081 /*
Vivek Goyal65b32a52009-12-16 17:52:59 -05002082 * check workload expiration, and that we still have other queues ready
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002083 */
Vivek Goyal65b32a52009-12-16 17:52:59 -05002084 if (count && !time_after(jiffies, cfqd->workload_expires))
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002085 return;
2086
2087 /* otherwise select new workload type */
2088 cfqd->serving_type =
Vivek Goyal65b32a52009-12-16 17:52:59 -05002089 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2090 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002091 count = st->count;
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002092
2093 /*
2094 * the workload slice is computed as a fraction of target latency
2095 * proportional to the number of queues in that workload, over
2096 * all the queues in the same priority class
2097 */
Vivek Goyal58ff82f2009-12-03 12:59:44 -05002098 group_slice = cfq_group_slice(cfqd, cfqg);
2099
2100 slice = group_slice * count /
2101 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2102 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002103
Vivek Goyalf26bd1f2009-12-03 12:59:54 -05002104 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2105 unsigned int tmp;
2106
2107 /*
2108 * Async queues are currently system wide. Just taking
2109 * proportion of queues with-in same group will lead to higher
2110 * async ratio system wide as generally root group is going
2111 * to have higher weight. A more accurate thing would be to
2112 * calculate system wide asnc/sync ratio.
2113 */
2114 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2115 tmp = tmp/cfqd->busy_queues;
2116 slice = min_t(unsigned, slice, tmp);
2117
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002118 /* async workload slice is scaled down according to
2119 * the sync/async slice ratio. */
2120 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
Vivek Goyalf26bd1f2009-12-03 12:59:54 -05002121 } else
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002122 /* sync workload slice is at least 2 * cfq_slice_idle */
2123 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2124
2125 slice = max_t(unsigned, slice, CFQ_MIN_TT);
Divyesh Shahb1ffe732010-03-25 15:45:03 +01002126 cfq_log(cfqd, "workload slice:%d", slice);
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002127 cfqd->workload_expires = jiffies + slice;
Corrado Zoccolo8e550632009-11-26 10:02:58 +01002128 cfqd->noidle_tree_requires_idle = false;
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002129}
2130
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002131static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2132{
2133 struct cfq_rb_root *st = &cfqd->grp_service_tree;
Vivek Goyal25bc6b02009-12-03 12:59:43 -05002134 struct cfq_group *cfqg;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002135
2136 if (RB_EMPTY_ROOT(&st->rb))
2137 return NULL;
Vivek Goyal25bc6b02009-12-03 12:59:43 -05002138 cfqg = cfq_rb_first_group(st);
2139 st->active = &cfqg->rb_node;
2140 update_min_vdisktime(st);
2141 return cfqg;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002142}
2143
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002144static void cfq_choose_cfqg(struct cfq_data *cfqd)
2145{
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002146 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2147
2148 cfqd->serving_group = cfqg;
Vivek Goyaldae739e2009-12-03 12:59:45 -05002149
2150 /* Restore the workload type data */
2151 if (cfqg->saved_workload_slice) {
2152 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2153 cfqd->serving_type = cfqg->saved_workload;
2154 cfqd->serving_prio = cfqg->saved_serving_prio;
Gui Jianfeng66ae2912009-12-15 10:08:45 +01002155 } else
2156 cfqd->workload_expires = jiffies - 1;
2157
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05002158 choose_service_tree(cfqd, cfqg);
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002159}
2160
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002161/*
Jens Axboe498d3aa2007-04-26 12:54:48 +02002162 * Select a queue for service. If we have a current active queue,
2163 * check whether to continue servicing it, or retrieve and set a new one.
Jens Axboe22e2c502005-06-27 10:55:12 +02002164 */
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01002165static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
Jens Axboe22e2c502005-06-27 10:55:12 +02002166{
Jens Axboea36e71f2009-04-15 12:15:11 +02002167 struct cfq_queue *cfqq, *new_cfqq = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +02002168
2169 cfqq = cfqd->active_queue;
2170 if (!cfqq)
2171 goto new_queue;
2172
Vivek Goyalf04a6422009-12-03 12:59:40 -05002173 if (!cfqd->rq_queued)
2174 return NULL;
Vivek Goyalc244bb52009-12-08 17:52:57 -05002175
2176 /*
2177 * We were waiting for group to get backlogged. Expire the queue
2178 */
2179 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2180 goto expire;
2181
Jens Axboe22e2c502005-06-27 10:55:12 +02002182 /*
Jens Axboe6d048f52007-04-25 12:44:27 +02002183 * The active queue has run out of time, expire it and select new.
Jens Axboe22e2c502005-06-27 10:55:12 +02002184 */
Vivek Goyal7667aa02009-12-08 17:52:58 -05002185 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2186 /*
2187 * If slice had not expired at the completion of last request
2188 * we might not have turned on wait_busy flag. Don't expire
2189 * the queue yet. Allow the group to get backlogged.
2190 *
2191 * The very fact that we have used the slice, that means we
2192 * have been idling all along on this queue and it should be
2193 * ok to wait for this request to complete.
2194 */
Vivek Goyal82bbbf22009-12-10 19:25:41 +01002195 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2196 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2197 cfqq = NULL;
Vivek Goyal7667aa02009-12-08 17:52:58 -05002198 goto keep_queue;
Vivek Goyal82bbbf22009-12-10 19:25:41 +01002199 } else
Vivek Goyal7667aa02009-12-08 17:52:58 -05002200 goto expire;
2201 }
Jens Axboe22e2c502005-06-27 10:55:12 +02002202
2203 /*
Jens Axboe6d048f52007-04-25 12:44:27 +02002204 * The active queue has requests and isn't expired, allow it to
2205 * dispatch.
Jens Axboe22e2c502005-06-27 10:55:12 +02002206 */
Jens Axboedd67d052006-06-21 09:36:18 +02002207 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
Jens Axboe22e2c502005-06-27 10:55:12 +02002208 goto keep_queue;
Jens Axboe6d048f52007-04-25 12:44:27 +02002209
2210 /*
Jens Axboea36e71f2009-04-15 12:15:11 +02002211 * If another queue has a request waiting within our mean seek
2212 * distance, let it run. The expire code will check for close
2213 * cooperators and put the close queue at the front of the service
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002214 * tree. If possible, merge the expiring queue with the new cfqq.
Jens Axboea36e71f2009-04-15 12:15:11 +02002215 */
Jeff Moyerb3b6d042009-10-23 17:14:51 -04002216 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002217 if (new_cfqq) {
2218 if (!cfqq->new_cfqq)
2219 cfq_setup_merge(cfqq, new_cfqq);
Jens Axboea36e71f2009-04-15 12:15:11 +02002220 goto expire;
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002221 }
Jens Axboea36e71f2009-04-15 12:15:11 +02002222
2223 /*
Jens Axboe6d048f52007-04-25 12:44:27 +02002224 * No requests pending. If the active queue still has requests in
2225 * flight or is idling for a new request, allow either of these
2226 * conditions to happen (or time out) before selecting a new queue.
2227 */
Jens Axboecc197472007-04-20 20:45:39 +02002228 if (timer_pending(&cfqd->idle_slice_timer) ||
Corrado Zoccoloa6d44e92009-10-26 22:45:11 +01002229 (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) {
Jens Axboecaaa5f92006-06-16 11:23:00 +02002230 cfqq = NULL;
2231 goto keep_queue;
Jens Axboe22e2c502005-06-27 10:55:12 +02002232 }
2233
Jens Axboe3b181522005-06-27 10:56:24 +02002234expire:
Vivek Goyale5ff0822010-04-26 19:25:11 +02002235 cfq_slice_expired(cfqd, 0);
Jens Axboe3b181522005-06-27 10:56:24 +02002236new_queue:
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002237 /*
2238 * Current queue expired. Check if we have to switch to a new
2239 * service tree
2240 */
2241 if (!new_cfqq)
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002242 cfq_choose_cfqg(cfqd);
Corrado Zoccolo718eee02009-10-26 22:45:29 +01002243
Jens Axboea36e71f2009-04-15 12:15:11 +02002244 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02002245keep_queue:
Jens Axboe3b181522005-06-27 10:56:24 +02002246 return cfqq;
Jens Axboe22e2c502005-06-27 10:55:12 +02002247}
2248
Jens Axboefebffd62008-01-28 13:19:43 +01002249static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
Jens Axboed9e76202007-04-20 14:27:50 +02002250{
2251 int dispatched = 0;
2252
2253 while (cfqq->next_rq) {
2254 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2255 dispatched++;
2256 }
2257
2258 BUG_ON(!list_empty(&cfqq->fifo));
Vivek Goyalf04a6422009-12-03 12:59:40 -05002259
2260 /* By default cfqq is not expired if it is empty. Do it explicitly */
Vivek Goyale5ff0822010-04-26 19:25:11 +02002261 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
Jens Axboed9e76202007-04-20 14:27:50 +02002262 return dispatched;
2263}
2264
Jens Axboe498d3aa2007-04-26 12:54:48 +02002265/*
2266 * Drain our current requests. Used for barriers and when switching
2267 * io schedulers on-the-fly.
2268 */
Jens Axboed9e76202007-04-20 14:27:50 +02002269static int cfq_forced_dispatch(struct cfq_data *cfqd)
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01002270{
Jens Axboe08717142008-01-28 11:38:15 +01002271 struct cfq_queue *cfqq;
Jens Axboed9e76202007-04-20 14:27:50 +02002272 int dispatched = 0;
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002273
Divyesh Shah3440c492010-04-09 09:29:57 +02002274 /* Expire the timeslice of the current active queue first */
Vivek Goyale5ff0822010-04-26 19:25:11 +02002275 cfq_slice_expired(cfqd, 0);
Divyesh Shah3440c492010-04-09 09:29:57 +02002276 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2277 __cfq_set_active_queue(cfqd, cfqq);
Vivek Goyalf04a6422009-12-03 12:59:40 -05002278 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
Divyesh Shah3440c492010-04-09 09:29:57 +02002279 }
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01002280
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01002281 BUG_ON(cfqd->busy_queues);
2282
Jeff Moyer69237152009-06-12 15:29:30 +02002283 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
Tejun Heo1b5ed5e12005-11-10 08:49:19 +01002284 return dispatched;
2285}
2286
Shaohua Liabc3c742010-03-01 09:20:54 +01002287static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2288 struct cfq_queue *cfqq)
2289{
2290 /* the queue hasn't finished any request, can't estimate */
2291 if (cfq_cfqq_slice_new(cfqq))
2292 return 1;
2293 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2294 cfqq->slice_end))
2295 return 1;
2296
2297 return 0;
2298}
2299
Jens Axboe0b182d62009-10-06 20:49:37 +02002300static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
Jens Axboe2f5cb732009-04-07 08:51:19 +02002301{
Jens Axboe2f5cb732009-04-07 08:51:19 +02002302 unsigned int max_dispatch;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002303
Jens Axboe2f5cb732009-04-07 08:51:19 +02002304 /*
Jens Axboe5ad531d2009-07-03 12:57:48 +02002305 * Drain async requests before we start sync IO
2306 */
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01002307 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
Jens Axboe0b182d62009-10-06 20:49:37 +02002308 return false;
Jens Axboe5ad531d2009-07-03 12:57:48 +02002309
2310 /*
Jens Axboe2f5cb732009-04-07 08:51:19 +02002311 * If this is an async queue and we have sync IO in flight, let it wait
2312 */
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01002313 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
Jens Axboe0b182d62009-10-06 20:49:37 +02002314 return false;
Jens Axboe2f5cb732009-04-07 08:51:19 +02002315
Shaohua Liabc3c742010-03-01 09:20:54 +01002316 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
Jens Axboe2f5cb732009-04-07 08:51:19 +02002317 if (cfq_class_idle(cfqq))
2318 max_dispatch = 1;
2319
2320 /*
2321 * Does this cfqq already have too much IO in flight?
2322 */
2323 if (cfqq->dispatched >= max_dispatch) {
2324 /*
2325 * idle queue must always only have a single IO in flight
2326 */
Jens Axboe3ed9a292007-04-23 08:33:33 +02002327 if (cfq_class_idle(cfqq))
Jens Axboe0b182d62009-10-06 20:49:37 +02002328 return false;
Jens Axboe3ed9a292007-04-23 08:33:33 +02002329
Jens Axboe2f5cb732009-04-07 08:51:19 +02002330 /*
2331 * We have other queues, don't allow more IO from this one
2332 */
Shaohua Liabc3c742010-03-01 09:20:54 +01002333 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq))
Jens Axboe0b182d62009-10-06 20:49:37 +02002334 return false;
Jens Axboe9ede2092007-01-19 12:11:44 +11002335
Jens Axboe2f5cb732009-04-07 08:51:19 +02002336 /*
Shaohua Li474b18c2009-12-03 12:58:05 +01002337 * Sole queue user, no limit
Vivek Goyal365722b2009-10-03 15:21:27 +02002338 */
Shaohua Liabc3c742010-03-01 09:20:54 +01002339 if (cfqd->busy_queues == 1)
2340 max_dispatch = -1;
2341 else
2342 /*
2343 * Normally we start throttling cfqq when cfq_quantum/2
2344 * requests have been dispatched. But we can drive
2345 * deeper queue depths at the beginning of slice
2346 * subjected to upper limit of cfq_quantum.
2347 * */
2348 max_dispatch = cfqd->cfq_quantum;
Jens Axboe8e296752009-10-03 16:26:03 +02002349 }
2350
2351 /*
2352 * Async queues must wait a bit before being allowed dispatch.
2353 * We also ramp up the dispatch depth gradually for async IO,
2354 * based on the last sync IO we serviced
2355 */
Jens Axboe963b72f2009-10-03 19:42:18 +02002356 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
Corrado Zoccolo573412b2009-12-06 11:48:52 +01002357 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
Jens Axboe8e296752009-10-03 16:26:03 +02002358 unsigned int depth;
Vivek Goyal365722b2009-10-03 15:21:27 +02002359
Jens Axboe61f0c1d2009-10-03 19:46:03 +02002360 depth = last_sync / cfqd->cfq_slice[1];
Jens Axboee00c54c2009-10-04 20:36:19 +02002361 if (!depth && !cfqq->dispatched)
2362 depth = 1;
Jens Axboe8e296752009-10-03 16:26:03 +02002363 if (depth < max_dispatch)
2364 max_dispatch = depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365 }
2366
Jens Axboe0b182d62009-10-06 20:49:37 +02002367 /*
2368 * If we're below the current max, allow a dispatch
2369 */
2370 return cfqq->dispatched < max_dispatch;
2371}
2372
2373/*
2374 * Dispatch a request from cfqq, moving them to the request queue
2375 * dispatch list.
2376 */
2377static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2378{
2379 struct request *rq;
2380
2381 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2382
2383 if (!cfq_may_dispatch(cfqd, cfqq))
2384 return false;
2385
2386 /*
2387 * follow expired path, else get first next available
2388 */
2389 rq = cfq_check_fifo(cfqq);
2390 if (!rq)
2391 rq = cfqq->next_rq;
2392
2393 /*
2394 * insert request into driver dispatch list
2395 */
2396 cfq_dispatch_insert(cfqd->queue, rq);
2397
2398 if (!cfqd->active_cic) {
2399 struct cfq_io_context *cic = RQ_CIC(rq);
2400
2401 atomic_long_inc(&cic->ioc->refcount);
2402 cfqd->active_cic = cic;
2403 }
2404
2405 return true;
2406}
2407
2408/*
2409 * Find the cfqq that we need to service and move a request from that to the
2410 * dispatch list
2411 */
2412static int cfq_dispatch_requests(struct request_queue *q, int force)
2413{
2414 struct cfq_data *cfqd = q->elevator->elevator_data;
2415 struct cfq_queue *cfqq;
2416
2417 if (!cfqd->busy_queues)
2418 return 0;
2419
2420 if (unlikely(force))
2421 return cfq_forced_dispatch(cfqd);
2422
2423 cfqq = cfq_select_queue(cfqd);
2424 if (!cfqq)
Jens Axboe8e296752009-10-03 16:26:03 +02002425 return 0;
2426
Jens Axboe2f5cb732009-04-07 08:51:19 +02002427 /*
Jens Axboe0b182d62009-10-06 20:49:37 +02002428 * Dispatch a request from this cfqq, if it is allowed
Jens Axboe2f5cb732009-04-07 08:51:19 +02002429 */
Jens Axboe0b182d62009-10-06 20:49:37 +02002430 if (!cfq_dispatch_request(cfqd, cfqq))
2431 return 0;
2432
Jens Axboe2f5cb732009-04-07 08:51:19 +02002433 cfqq->slice_dispatch++;
Jens Axboeb0291952009-04-07 11:38:31 +02002434 cfq_clear_cfqq_must_dispatch(cfqq);
Jens Axboe2f5cb732009-04-07 08:51:19 +02002435
2436 /*
2437 * expire an async queue immediately if it has used up its slice. idle
2438 * queue always expire after 1 dispatch round.
2439 */
2440 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2441 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2442 cfq_class_idle(cfqq))) {
2443 cfqq->slice_end = jiffies + 1;
Vivek Goyale5ff0822010-04-26 19:25:11 +02002444 cfq_slice_expired(cfqd, 0);
Jens Axboe2f5cb732009-04-07 08:51:19 +02002445 }
2446
Shan Weib217a902009-09-01 10:06:42 +02002447 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
Jens Axboe2f5cb732009-04-07 08:51:19 +02002448 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002449}
2450
Linus Torvalds1da177e2005-04-16 15:20:36 -07002451/*
Jens Axboe5e705372006-07-13 12:39:25 +02002452 * task holds one reference to the queue, dropped when task exits. each rq
2453 * in-flight on this queue also holds a reference, dropped when rq is freed.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002454 *
Vivek Goyalb1c35762009-12-03 12:59:47 -05002455 * Each cfq queue took a reference on the parent group. Drop it now.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002456 * queue lock must be held here.
2457 */
2458static void cfq_put_queue(struct cfq_queue *cfqq)
2459{
Jens Axboe22e2c502005-06-27 10:55:12 +02002460 struct cfq_data *cfqd = cfqq->cfqd;
Vivek Goyal878eadd2009-12-07 19:37:15 +01002461 struct cfq_group *cfqg, *orig_cfqg;
Jens Axboe22e2c502005-06-27 10:55:12 +02002462
2463 BUG_ON(atomic_read(&cfqq->ref) <= 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002464
2465 if (!atomic_dec_and_test(&cfqq->ref))
2466 return;
2467
Jens Axboe7b679132008-05-30 12:23:07 +02002468 cfq_log_cfqq(cfqd, cfqq, "put_queue");
Linus Torvalds1da177e2005-04-16 15:20:36 -07002469 BUG_ON(rb_first(&cfqq->sort_list));
Jens Axboe22e2c502005-06-27 10:55:12 +02002470 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
Vivek Goyalb1c35762009-12-03 12:59:47 -05002471 cfqg = cfqq->cfqg;
Vivek Goyal878eadd2009-12-07 19:37:15 +01002472 orig_cfqg = cfqq->orig_cfqg;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473
Jens Axboe28f95cbc2007-01-19 12:09:53 +11002474 if (unlikely(cfqd->active_queue == cfqq)) {
Vivek Goyale5ff0822010-04-26 19:25:11 +02002475 __cfq_slice_expired(cfqd, cfqq, 0);
Jens Axboe23e018a2009-10-05 08:52:35 +02002476 cfq_schedule_dispatch(cfqd);
Jens Axboe28f95cbc2007-01-19 12:09:53 +11002477 }
Jens Axboe22e2c502005-06-27 10:55:12 +02002478
Vivek Goyalf04a6422009-12-03 12:59:40 -05002479 BUG_ON(cfq_cfqq_on_rr(cfqq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002480 kmem_cache_free(cfq_pool, cfqq);
Vivek Goyalb1c35762009-12-03 12:59:47 -05002481 cfq_put_cfqg(cfqg);
Vivek Goyal878eadd2009-12-07 19:37:15 +01002482 if (orig_cfqg)
2483 cfq_put_cfqg(orig_cfqg);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002484}
2485
Jens Axboed6de8be2008-05-28 14:46:59 +02002486/*
2487 * Must always be called with the rcu_read_lock() held
2488 */
Jens Axboe07416d22008-05-07 09:17:12 +02002489static void
2490__call_for_each_cic(struct io_context *ioc,
2491 void (*func)(struct io_context *, struct cfq_io_context *))
2492{
2493 struct cfq_io_context *cic;
2494 struct hlist_node *n;
2495
2496 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2497 func(ioc, cic);
2498}
2499
Jens Axboe4ac845a2008-01-24 08:44:49 +01002500/*
Fabio Checconi34e6bbf2008-04-02 14:31:02 +02002501 * Call func for each cic attached to this ioc.
Jens Axboe4ac845a2008-01-24 08:44:49 +01002502 */
Fabio Checconi34e6bbf2008-04-02 14:31:02 +02002503static void
Jens Axboe4ac845a2008-01-24 08:44:49 +01002504call_for_each_cic(struct io_context *ioc,
2505 void (*func)(struct io_context *, struct cfq_io_context *))
2506{
Jens Axboe4ac845a2008-01-24 08:44:49 +01002507 rcu_read_lock();
Jens Axboe07416d22008-05-07 09:17:12 +02002508 __call_for_each_cic(ioc, func);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002509 rcu_read_unlock();
Fabio Checconi34e6bbf2008-04-02 14:31:02 +02002510}
Jens Axboe4ac845a2008-01-24 08:44:49 +01002511
Fabio Checconi34e6bbf2008-04-02 14:31:02 +02002512static void cfq_cic_free_rcu(struct rcu_head *head)
2513{
2514 struct cfq_io_context *cic;
2515
2516 cic = container_of(head, struct cfq_io_context, rcu_head);
2517
2518 kmem_cache_free(cfq_ioc_pool, cic);
Tejun Heo245b2e72009-06-24 15:13:48 +09002519 elv_ioc_count_dec(cfq_ioc_count);
Fabio Checconi34e6bbf2008-04-02 14:31:02 +02002520
Jens Axboe9a11b4e2008-05-29 09:32:08 +02002521 if (ioc_gone) {
2522 /*
2523 * CFQ scheduler is exiting, grab exit lock and check
2524 * the pending io context count. If it hits zero,
2525 * complete ioc_gone and set it back to NULL
2526 */
2527 spin_lock(&ioc_gone_lock);
Tejun Heo245b2e72009-06-24 15:13:48 +09002528 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
Jens Axboe9a11b4e2008-05-29 09:32:08 +02002529 complete(ioc_gone);
2530 ioc_gone = NULL;
2531 }
2532 spin_unlock(&ioc_gone_lock);
2533 }
Fabio Checconi34e6bbf2008-04-02 14:31:02 +02002534}
2535
2536static void cfq_cic_free(struct cfq_io_context *cic)
2537{
2538 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002539}
2540
2541static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2542{
2543 unsigned long flags;
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002544 unsigned long dead_key = (unsigned long) cic->key;
Jens Axboe4ac845a2008-01-24 08:44:49 +01002545
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002546 BUG_ON(!(dead_key & CIC_DEAD_KEY));
Jens Axboe4ac845a2008-01-24 08:44:49 +01002547
2548 spin_lock_irqsave(&ioc->lock, flags);
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +04002549 radix_tree_delete(&ioc->radix_root, dead_key >> CIC_DEAD_INDEX_SHIFT);
Jens Axboeffc4e752008-02-19 10:02:29 +01002550 hlist_del_rcu(&cic->cic_list);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002551 spin_unlock_irqrestore(&ioc->lock, flags);
2552
Fabio Checconi34e6bbf2008-04-02 14:31:02 +02002553 cfq_cic_free(cic);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002554}
2555
Jens Axboed6de8be2008-05-28 14:46:59 +02002556/*
2557 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2558 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2559 * and ->trim() which is called with the task lock held
2560 */
Jens Axboee2d74ac2006-03-28 08:59:01 +02002561static void cfq_free_io_context(struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562{
Jens Axboe4ac845a2008-01-24 08:44:49 +01002563 /*
Fabio Checconi34e6bbf2008-04-02 14:31:02 +02002564 * ioc->refcount is zero here, or we are called from elv_unregister(),
2565 * so no more cic's are allowed to be linked into this ioc. So it
2566 * should be ok to iterate over the known list, we will see all cic's
2567 * since no new ones are added.
Jens Axboe4ac845a2008-01-24 08:44:49 +01002568 */
Jens Axboe07416d22008-05-07 09:17:12 +02002569 __call_for_each_cic(ioc, cic_free_func);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002570}
2571
Shaohua Lid02a2c02010-05-25 10:16:53 +02002572static void cfq_put_cooperator(struct cfq_queue *cfqq)
Jens Axboe89850f72006-07-22 16:48:31 +02002573{
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002574 struct cfq_queue *__cfqq, *next;
2575
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002576 /*
2577 * If this queue was scheduled to merge with another queue, be
2578 * sure to drop the reference taken on that queue (and others in
2579 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2580 */
2581 __cfqq = cfqq->new_cfqq;
2582 while (__cfqq) {
2583 if (__cfqq == cfqq) {
2584 WARN(1, "cfqq->new_cfqq loop detected\n");
2585 break;
2586 }
2587 next = __cfqq->new_cfqq;
2588 cfq_put_queue(__cfqq);
2589 __cfqq = next;
2590 }
Shaohua Lid02a2c02010-05-25 10:16:53 +02002591}
2592
2593static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2594{
2595 if (unlikely(cfqq == cfqd->active_queue)) {
2596 __cfq_slice_expired(cfqd, cfqq, 0);
2597 cfq_schedule_dispatch(cfqd);
2598 }
2599
2600 cfq_put_cooperator(cfqq);
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04002601
Jens Axboe89850f72006-07-22 16:48:31 +02002602 cfq_put_queue(cfqq);
2603}
2604
2605static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2606 struct cfq_io_context *cic)
2607{
Fabio Checconi4faa3c82008-04-10 08:28:01 +02002608 struct io_context *ioc = cic->ioc;
2609
Jens Axboefc463792006-08-29 09:05:44 +02002610 list_del_init(&cic->queue_list);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002611
2612 /*
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002613 * Make sure dead mark is seen for dead queues
Jens Axboe4ac845a2008-01-24 08:44:49 +01002614 */
Jens Axboefc463792006-08-29 09:05:44 +02002615 smp_wmb();
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002616 cic->key = cfqd_dead_key(cfqd);
Jens Axboefc463792006-08-29 09:05:44 +02002617
Fabio Checconi4faa3c82008-04-10 08:28:01 +02002618 if (ioc->ioc_data == cic)
2619 rcu_assign_pointer(ioc->ioc_data, NULL);
2620
Jens Axboeff6657c2009-04-08 10:58:57 +02002621 if (cic->cfqq[BLK_RW_ASYNC]) {
2622 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2623 cic->cfqq[BLK_RW_ASYNC] = NULL;
Jens Axboe89850f72006-07-22 16:48:31 +02002624 }
2625
Jens Axboeff6657c2009-04-08 10:58:57 +02002626 if (cic->cfqq[BLK_RW_SYNC]) {
2627 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2628 cic->cfqq[BLK_RW_SYNC] = NULL;
Jens Axboe89850f72006-07-22 16:48:31 +02002629 }
Jens Axboe89850f72006-07-22 16:48:31 +02002630}
2631
Jens Axboe4ac845a2008-01-24 08:44:49 +01002632static void cfq_exit_single_io_context(struct io_context *ioc,
2633 struct cfq_io_context *cic)
Jens Axboe22e2c502005-06-27 10:55:12 +02002634{
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002635 struct cfq_data *cfqd = cic_to_cfqd(cic);
Jens Axboe22e2c502005-06-27 10:55:12 +02002636
Jens Axboe89850f72006-07-22 16:48:31 +02002637 if (cfqd) {
Jens Axboe165125e2007-07-24 09:28:11 +02002638 struct request_queue *q = cfqd->queue;
Jens Axboe4ac845a2008-01-24 08:44:49 +01002639 unsigned long flags;
Jens Axboe22e2c502005-06-27 10:55:12 +02002640
Jens Axboe4ac845a2008-01-24 08:44:49 +01002641 spin_lock_irqsave(q->queue_lock, flags);
Jens Axboe62c1fe92008-12-15 21:19:25 +01002642
2643 /*
2644 * Ensure we get a fresh copy of the ->key to prevent
2645 * race between exiting task and queue
2646 */
2647 smp_read_barrier_depends();
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002648 if (cic->key == cfqd)
Jens Axboe62c1fe92008-12-15 21:19:25 +01002649 __cfq_exit_single_io_context(cfqd, cic);
2650
Jens Axboe4ac845a2008-01-24 08:44:49 +01002651 spin_unlock_irqrestore(q->queue_lock, flags);
Al Viro12a05732006-03-18 13:38:01 -05002652 }
Jens Axboe22e2c502005-06-27 10:55:12 +02002653}
2654
Jens Axboe498d3aa2007-04-26 12:54:48 +02002655/*
2656 * The process that ioc belongs to has exited, we need to clean up
2657 * and put the internal structures we have that belongs to that process.
2658 */
Jens Axboee2d74ac2006-03-28 08:59:01 +02002659static void cfq_exit_io_context(struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002660{
Jens Axboe4ac845a2008-01-24 08:44:49 +01002661 call_for_each_cic(ioc, cfq_exit_single_io_context);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002662}
2663
Jens Axboe22e2c502005-06-27 10:55:12 +02002664static struct cfq_io_context *
Al Viro8267e262005-10-21 03:20:53 -04002665cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002666{
Jens Axboeb5deef92006-07-19 23:39:40 +02002667 struct cfq_io_context *cic;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002668
Christoph Lameter94f60302007-07-17 04:03:29 -07002669 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2670 cfqd->queue->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002671 if (cic) {
Jens Axboe22e2c502005-06-27 10:55:12 +02002672 cic->last_end_request = jiffies;
Jens Axboe553698f2006-06-14 19:11:57 +02002673 INIT_LIST_HEAD(&cic->queue_list);
Jens Axboeffc4e752008-02-19 10:02:29 +01002674 INIT_HLIST_NODE(&cic->cic_list);
Jens Axboe22e2c502005-06-27 10:55:12 +02002675 cic->dtor = cfq_free_io_context;
2676 cic->exit = cfq_exit_io_context;
Tejun Heo245b2e72009-06-24 15:13:48 +09002677 elv_ioc_count_inc(cfq_ioc_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002678 }
2679
2680 return cic;
2681}
2682
Jens Axboefd0928d2008-01-24 08:52:45 +01002683static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
Jens Axboe22e2c502005-06-27 10:55:12 +02002684{
2685 struct task_struct *tsk = current;
2686 int ioprio_class;
2687
Jens Axboe3b181522005-06-27 10:56:24 +02002688 if (!cfq_cfqq_prio_changed(cfqq))
Jens Axboe22e2c502005-06-27 10:55:12 +02002689 return;
2690
Jens Axboefd0928d2008-01-24 08:52:45 +01002691 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
Jens Axboe22e2c502005-06-27 10:55:12 +02002692 switch (ioprio_class) {
Jens Axboefe094d92008-01-31 13:08:54 +01002693 default:
2694 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2695 case IOPRIO_CLASS_NONE:
2696 /*
Jens Axboe6d63c272008-05-07 09:51:23 +02002697 * no prio set, inherit CPU scheduling settings
Jens Axboefe094d92008-01-31 13:08:54 +01002698 */
2699 cfqq->ioprio = task_nice_ioprio(tsk);
Jens Axboe6d63c272008-05-07 09:51:23 +02002700 cfqq->ioprio_class = task_nice_ioclass(tsk);
Jens Axboefe094d92008-01-31 13:08:54 +01002701 break;
2702 case IOPRIO_CLASS_RT:
2703 cfqq->ioprio = task_ioprio(ioc);
2704 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2705 break;
2706 case IOPRIO_CLASS_BE:
2707 cfqq->ioprio = task_ioprio(ioc);
2708 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2709 break;
2710 case IOPRIO_CLASS_IDLE:
2711 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2712 cfqq->ioprio = 7;
2713 cfq_clear_cfqq_idle_window(cfqq);
2714 break;
Jens Axboe22e2c502005-06-27 10:55:12 +02002715 }
2716
2717 /*
2718 * keep track of original prio settings in case we have to temporarily
2719 * elevate the priority of this queue
2720 */
2721 cfqq->org_ioprio = cfqq->ioprio;
2722 cfqq->org_ioprio_class = cfqq->ioprio_class;
Jens Axboe3b181522005-06-27 10:56:24 +02002723 cfq_clear_cfqq_prio_changed(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02002724}
2725
Jens Axboefebffd62008-01-28 13:19:43 +01002726static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
Jens Axboe22e2c502005-06-27 10:55:12 +02002727{
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002728 struct cfq_data *cfqd = cic_to_cfqd(cic);
Al Viro478a82b2006-03-18 13:25:24 -05002729 struct cfq_queue *cfqq;
Jens Axboec1b707d2006-10-30 19:54:23 +01002730 unsigned long flags;
Jens Axboe35e60772006-06-14 09:10:45 +02002731
Jens Axboecaaa5f92006-06-16 11:23:00 +02002732 if (unlikely(!cfqd))
2733 return;
2734
Jens Axboec1b707d2006-10-30 19:54:23 +01002735 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
Jens Axboecaaa5f92006-06-16 11:23:00 +02002736
Jens Axboeff6657c2009-04-08 10:58:57 +02002737 cfqq = cic->cfqq[BLK_RW_ASYNC];
Jens Axboecaaa5f92006-06-16 11:23:00 +02002738 if (cfqq) {
2739 struct cfq_queue *new_cfqq;
Jens Axboeff6657c2009-04-08 10:58:57 +02002740 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2741 GFP_ATOMIC);
Jens Axboecaaa5f92006-06-16 11:23:00 +02002742 if (new_cfqq) {
Jens Axboeff6657c2009-04-08 10:58:57 +02002743 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
Jens Axboecaaa5f92006-06-16 11:23:00 +02002744 cfq_put_queue(cfqq);
2745 }
Jens Axboe22e2c502005-06-27 10:55:12 +02002746 }
Jens Axboecaaa5f92006-06-16 11:23:00 +02002747
Jens Axboeff6657c2009-04-08 10:58:57 +02002748 cfqq = cic->cfqq[BLK_RW_SYNC];
Jens Axboecaaa5f92006-06-16 11:23:00 +02002749 if (cfqq)
2750 cfq_mark_cfqq_prio_changed(cfqq);
2751
Jens Axboec1b707d2006-10-30 19:54:23 +01002752 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
Jens Axboe22e2c502005-06-27 10:55:12 +02002753}
2754
Jens Axboefc463792006-08-29 09:05:44 +02002755static void cfq_ioc_set_ioprio(struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002756{
Jens Axboe4ac845a2008-01-24 08:44:49 +01002757 call_for_each_cic(ioc, changed_ioprio);
Jens Axboefc463792006-08-29 09:05:44 +02002758 ioc->ioprio_changed = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002759}
2760
Jens Axboed5036d72009-06-26 10:44:34 +02002761static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Jens Axboea6151c32009-10-07 20:02:57 +02002762 pid_t pid, bool is_sync)
Jens Axboed5036d72009-06-26 10:44:34 +02002763{
2764 RB_CLEAR_NODE(&cfqq->rb_node);
2765 RB_CLEAR_NODE(&cfqq->p_node);
2766 INIT_LIST_HEAD(&cfqq->fifo);
2767
2768 atomic_set(&cfqq->ref, 0);
2769 cfqq->cfqd = cfqd;
2770
2771 cfq_mark_cfqq_prio_changed(cfqq);
2772
2773 if (is_sync) {
2774 if (!cfq_class_idle(cfqq))
2775 cfq_mark_cfqq_idle_window(cfqq);
2776 cfq_mark_cfqq_sync(cfqq);
2777 }
2778 cfqq->pid = pid;
2779}
2780
Vivek Goyal24610332009-12-03 12:59:51 -05002781#ifdef CONFIG_CFQ_GROUP_IOSCHED
2782static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2783{
2784 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002785 struct cfq_data *cfqd = cic_to_cfqd(cic);
Vivek Goyal24610332009-12-03 12:59:51 -05002786 unsigned long flags;
2787 struct request_queue *q;
2788
2789 if (unlikely(!cfqd))
2790 return;
2791
2792 q = cfqd->queue;
2793
2794 spin_lock_irqsave(q->queue_lock, flags);
2795
2796 if (sync_cfqq) {
2797 /*
2798 * Drop reference to sync queue. A new sync queue will be
2799 * assigned in new group upon arrival of a fresh request.
2800 */
2801 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2802 cic_set_cfqq(cic, NULL, 1);
2803 cfq_put_queue(sync_cfqq);
2804 }
2805
2806 spin_unlock_irqrestore(q->queue_lock, flags);
2807}
2808
2809static void cfq_ioc_set_cgroup(struct io_context *ioc)
2810{
2811 call_for_each_cic(ioc, changed_cgroup);
2812 ioc->cgroup_changed = 0;
2813}
2814#endif /* CONFIG_CFQ_GROUP_IOSCHED */
2815
Linus Torvalds1da177e2005-04-16 15:20:36 -07002816static struct cfq_queue *
Jens Axboea6151c32009-10-07 20:02:57 +02002817cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
Jens Axboefd0928d2008-01-24 08:52:45 +01002818 struct io_context *ioc, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002819{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002820 struct cfq_queue *cfqq, *new_cfqq = NULL;
Vasily Tarasov91fac312007-04-25 12:29:51 +02002821 struct cfq_io_context *cic;
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002822 struct cfq_group *cfqg;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002823
2824retry:
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002825 cfqg = cfq_get_cfqg(cfqd, 1);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002826 cic = cfq_cic_lookup(cfqd, ioc);
Vasily Tarasov91fac312007-04-25 12:29:51 +02002827 /* cic always exists here */
2828 cfqq = cic_to_cfqq(cic, is_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002829
Jens Axboe6118b702009-06-30 09:34:12 +02002830 /*
2831 * Always try a new alloc if we fell back to the OOM cfqq
2832 * originally, since it should just be a temporary situation.
2833 */
2834 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2835 cfqq = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002836 if (new_cfqq) {
2837 cfqq = new_cfqq;
2838 new_cfqq = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +02002839 } else if (gfp_mask & __GFP_WAIT) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002840 spin_unlock_irq(cfqd->queue->queue_lock);
Christoph Lameter94f60302007-07-17 04:03:29 -07002841 new_cfqq = kmem_cache_alloc_node(cfq_pool,
Jens Axboe6118b702009-06-30 09:34:12 +02002842 gfp_mask | __GFP_ZERO,
Christoph Lameter94f60302007-07-17 04:03:29 -07002843 cfqd->queue->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002844 spin_lock_irq(cfqd->queue->queue_lock);
Jens Axboe6118b702009-06-30 09:34:12 +02002845 if (new_cfqq)
2846 goto retry;
Jens Axboe22e2c502005-06-27 10:55:12 +02002847 } else {
Christoph Lameter94f60302007-07-17 04:03:29 -07002848 cfqq = kmem_cache_alloc_node(cfq_pool,
2849 gfp_mask | __GFP_ZERO,
2850 cfqd->queue->node);
Kiyoshi Ueda db3b5842005-06-17 16:15:10 +02002851 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002852
Jens Axboe6118b702009-06-30 09:34:12 +02002853 if (cfqq) {
2854 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2855 cfq_init_prio_data(cfqq, ioc);
Vivek Goyalcdb16e82009-12-03 12:59:38 -05002856 cfq_link_cfqq_cfqg(cfqq, cfqg);
Jens Axboe6118b702009-06-30 09:34:12 +02002857 cfq_log_cfqq(cfqd, cfqq, "alloced");
2858 } else
2859 cfqq = &cfqd->oom_cfqq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002860 }
2861
2862 if (new_cfqq)
2863 kmem_cache_free(cfq_pool, new_cfqq);
2864
Linus Torvalds1da177e2005-04-16 15:20:36 -07002865 return cfqq;
2866}
2867
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002868static struct cfq_queue **
2869cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2870{
Jens Axboefe094d92008-01-31 13:08:54 +01002871 switch (ioprio_class) {
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002872 case IOPRIO_CLASS_RT:
2873 return &cfqd->async_cfqq[0][ioprio];
2874 case IOPRIO_CLASS_BE:
2875 return &cfqd->async_cfqq[1][ioprio];
2876 case IOPRIO_CLASS_IDLE:
2877 return &cfqd->async_idle_cfqq;
2878 default:
2879 BUG();
2880 }
2881}
2882
Jens Axboe15c31be2007-07-10 13:43:25 +02002883static struct cfq_queue *
Jens Axboea6151c32009-10-07 20:02:57 +02002884cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
Jens Axboe15c31be2007-07-10 13:43:25 +02002885 gfp_t gfp_mask)
2886{
Jens Axboefd0928d2008-01-24 08:52:45 +01002887 const int ioprio = task_ioprio(ioc);
2888 const int ioprio_class = task_ioprio_class(ioc);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002889 struct cfq_queue **async_cfqq = NULL;
Jens Axboe15c31be2007-07-10 13:43:25 +02002890 struct cfq_queue *cfqq = NULL;
2891
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002892 if (!is_sync) {
2893 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2894 cfqq = *async_cfqq;
2895 }
2896
Jens Axboe6118b702009-06-30 09:34:12 +02002897 if (!cfqq)
Jens Axboefd0928d2008-01-24 08:52:45 +01002898 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
Jens Axboe15c31be2007-07-10 13:43:25 +02002899
2900 /*
2901 * pin the queue now that it's allocated, scheduler exit will prune it
2902 */
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002903 if (!is_sync && !(*async_cfqq)) {
Jens Axboe15c31be2007-07-10 13:43:25 +02002904 atomic_inc(&cfqq->ref);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02002905 *async_cfqq = cfqq;
Jens Axboe15c31be2007-07-10 13:43:25 +02002906 }
2907
2908 atomic_inc(&cfqq->ref);
2909 return cfqq;
2910}
2911
Jens Axboe498d3aa2007-04-26 12:54:48 +02002912/*
2913 * We drop cfq io contexts lazily, so we may find a dead one.
2914 */
OGAWA Hirofumidbecf3a2006-04-18 09:45:18 +02002915static void
Jens Axboe4ac845a2008-01-24 08:44:49 +01002916cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
2917 struct cfq_io_context *cic)
OGAWA Hirofumidbecf3a2006-04-18 09:45:18 +02002918{
Jens Axboe4ac845a2008-01-24 08:44:49 +01002919 unsigned long flags;
2920
Jens Axboefc463792006-08-29 09:05:44 +02002921 WARN_ON(!list_empty(&cic->queue_list));
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002922 BUG_ON(cic->key != cfqd_dead_key(cfqd));
Jens Axboe597bc482007-04-24 21:23:53 +02002923
Jens Axboe4ac845a2008-01-24 08:44:49 +01002924 spin_lock_irqsave(&ioc->lock, flags);
Jens Axboe597bc482007-04-24 21:23:53 +02002925
Fabio Checconi4faa3c82008-04-10 08:28:01 +02002926 BUG_ON(ioc->ioc_data == cic);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002927
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +04002928 radix_tree_delete(&ioc->radix_root, cfqd->cic_index);
Jens Axboeffc4e752008-02-19 10:02:29 +01002929 hlist_del_rcu(&cic->cic_list);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002930 spin_unlock_irqrestore(&ioc->lock, flags);
2931
2932 cfq_cic_free(cic);
OGAWA Hirofumidbecf3a2006-04-18 09:45:18 +02002933}
2934
Jens Axboee2d74ac2006-03-28 08:59:01 +02002935static struct cfq_io_context *
Jens Axboe4ac845a2008-01-24 08:44:49 +01002936cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
Jens Axboee2d74ac2006-03-28 08:59:01 +02002937{
Jens Axboee2d74ac2006-03-28 08:59:01 +02002938 struct cfq_io_context *cic;
Jens Axboed6de8be2008-05-28 14:46:59 +02002939 unsigned long flags;
Jens Axboee2d74ac2006-03-28 08:59:01 +02002940
Vasily Tarasov91fac312007-04-25 12:29:51 +02002941 if (unlikely(!ioc))
2942 return NULL;
2943
Jens Axboed6de8be2008-05-28 14:46:59 +02002944 rcu_read_lock();
2945
Jens Axboe597bc482007-04-24 21:23:53 +02002946 /*
2947 * we maintain a last-hit cache, to avoid browsing over the tree
2948 */
Jens Axboe4ac845a2008-01-24 08:44:49 +01002949 cic = rcu_dereference(ioc->ioc_data);
Jens Axboed6de8be2008-05-28 14:46:59 +02002950 if (cic && cic->key == cfqd) {
2951 rcu_read_unlock();
Jens Axboe597bc482007-04-24 21:23:53 +02002952 return cic;
Jens Axboed6de8be2008-05-28 14:46:59 +02002953 }
Jens Axboe597bc482007-04-24 21:23:53 +02002954
Jens Axboe4ac845a2008-01-24 08:44:49 +01002955 do {
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +04002956 cic = radix_tree_lookup(&ioc->radix_root, cfqd->cic_index);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002957 rcu_read_unlock();
2958 if (!cic)
2959 break;
Konstantin Khlebnikovbca4b912010-05-20 23:21:34 +04002960 if (unlikely(cic->key != cfqd)) {
Jens Axboe4ac845a2008-01-24 08:44:49 +01002961 cfq_drop_dead_cic(cfqd, ioc, cic);
Jens Axboed6de8be2008-05-28 14:46:59 +02002962 rcu_read_lock();
Jens Axboe4ac845a2008-01-24 08:44:49 +01002963 continue;
OGAWA Hirofumidbecf3a2006-04-18 09:45:18 +02002964 }
Jens Axboee2d74ac2006-03-28 08:59:01 +02002965
Jens Axboed6de8be2008-05-28 14:46:59 +02002966 spin_lock_irqsave(&ioc->lock, flags);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002967 rcu_assign_pointer(ioc->ioc_data, cic);
Jens Axboed6de8be2008-05-28 14:46:59 +02002968 spin_unlock_irqrestore(&ioc->lock, flags);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002969 break;
2970 } while (1);
Jens Axboee2d74ac2006-03-28 08:59:01 +02002971
Jens Axboe4ac845a2008-01-24 08:44:49 +01002972 return cic;
Jens Axboee2d74ac2006-03-28 08:59:01 +02002973}
2974
Jens Axboe4ac845a2008-01-24 08:44:49 +01002975/*
2976 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
2977 * the process specific cfq io context when entered from the block layer.
2978 * Also adds the cic to a per-cfqd list, used when this queue is removed.
2979 */
Jens Axboefebffd62008-01-28 13:19:43 +01002980static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
2981 struct cfq_io_context *cic, gfp_t gfp_mask)
Jens Axboee2d74ac2006-03-28 08:59:01 +02002982{
Jens Axboe0261d682006-10-30 19:07:48 +01002983 unsigned long flags;
Jens Axboe4ac845a2008-01-24 08:44:49 +01002984 int ret;
Jens Axboee2d74ac2006-03-28 08:59:01 +02002985
Jens Axboe4ac845a2008-01-24 08:44:49 +01002986 ret = radix_tree_preload(gfp_mask);
2987 if (!ret) {
2988 cic->ioc = ioc;
2989 cic->key = cfqd;
Jens Axboee2d74ac2006-03-28 08:59:01 +02002990
Jens Axboe4ac845a2008-01-24 08:44:49 +01002991 spin_lock_irqsave(&ioc->lock, flags);
2992 ret = radix_tree_insert(&ioc->radix_root,
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +04002993 cfqd->cic_index, cic);
Jens Axboeffc4e752008-02-19 10:02:29 +01002994 if (!ret)
2995 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
Jens Axboe4ac845a2008-01-24 08:44:49 +01002996 spin_unlock_irqrestore(&ioc->lock, flags);
2997
2998 radix_tree_preload_end();
2999
3000 if (!ret) {
3001 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3002 list_add(&cic->queue_list, &cfqd->cic_list);
3003 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
OGAWA Hirofumidbecf3a2006-04-18 09:45:18 +02003004 }
Jens Axboee2d74ac2006-03-28 08:59:01 +02003005 }
3006
Jens Axboe4ac845a2008-01-24 08:44:49 +01003007 if (ret)
3008 printk(KERN_ERR "cfq: cic link failed!\n");
Jens Axboefc463792006-08-29 09:05:44 +02003009
Jens Axboe4ac845a2008-01-24 08:44:49 +01003010 return ret;
Jens Axboee2d74ac2006-03-28 08:59:01 +02003011}
3012
Jens Axboe22e2c502005-06-27 10:55:12 +02003013/*
3014 * Setup general io context and cfq io context. There can be several cfq
3015 * io contexts per general io context, if this process is doing io to more
Jens Axboee2d74ac2006-03-28 08:59:01 +02003016 * than one device managed by cfq.
Jens Axboe22e2c502005-06-27 10:55:12 +02003017 */
3018static struct cfq_io_context *
Jens Axboee2d74ac2006-03-28 08:59:01 +02003019cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003020{
Jens Axboe22e2c502005-06-27 10:55:12 +02003021 struct io_context *ioc = NULL;
3022 struct cfq_io_context *cic;
3023
3024 might_sleep_if(gfp_mask & __GFP_WAIT);
3025
Jens Axboeb5deef92006-07-19 23:39:40 +02003026 ioc = get_io_context(gfp_mask, cfqd->queue->node);
Jens Axboe22e2c502005-06-27 10:55:12 +02003027 if (!ioc)
3028 return NULL;
3029
Jens Axboe4ac845a2008-01-24 08:44:49 +01003030 cic = cfq_cic_lookup(cfqd, ioc);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003031 if (cic)
3032 goto out;
Jens Axboe22e2c502005-06-27 10:55:12 +02003033
Jens Axboee2d74ac2006-03-28 08:59:01 +02003034 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3035 if (cic == NULL)
3036 goto err;
Jens Axboe22e2c502005-06-27 10:55:12 +02003037
Jens Axboe4ac845a2008-01-24 08:44:49 +01003038 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
3039 goto err_free;
3040
Jens Axboe22e2c502005-06-27 10:55:12 +02003041out:
Jens Axboefc463792006-08-29 09:05:44 +02003042 smp_read_barrier_depends();
3043 if (unlikely(ioc->ioprio_changed))
3044 cfq_ioc_set_ioprio(ioc);
3045
Vivek Goyal24610332009-12-03 12:59:51 -05003046#ifdef CONFIG_CFQ_GROUP_IOSCHED
3047 if (unlikely(ioc->cgroup_changed))
3048 cfq_ioc_set_cgroup(ioc);
3049#endif
Jens Axboe22e2c502005-06-27 10:55:12 +02003050 return cic;
Jens Axboe4ac845a2008-01-24 08:44:49 +01003051err_free:
3052 cfq_cic_free(cic);
Jens Axboe22e2c502005-06-27 10:55:12 +02003053err:
3054 put_io_context(ioc);
3055 return NULL;
3056}
3057
3058static void
3059cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
3060{
Jens Axboeaaf12282007-01-19 11:30:16 +11003061 unsigned long elapsed = jiffies - cic->last_end_request;
3062 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
Jens Axboe22e2c502005-06-27 10:55:12 +02003063
3064 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
3065 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
3066 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
3067}
3068
Jens Axboe206dc692006-03-28 13:03:44 +02003069static void
Jeff Moyerb2c18e12009-10-23 17:14:49 -04003070cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
Jens Axboe6d048f52007-04-25 12:44:27 +02003071 struct request *rq)
Jens Axboe206dc692006-03-28 13:03:44 +02003072{
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +01003073 sector_t sdist = 0;
Corrado Zoccolo41647e72010-02-27 19:45:40 +01003074 sector_t n_sec = blk_rq_sectors(rq);
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +01003075 if (cfqq->last_request_pos) {
3076 if (cfqq->last_request_pos < blk_rq_pos(rq))
3077 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3078 else
3079 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3080 }
Jens Axboe206dc692006-03-28 13:03:44 +02003081
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +01003082 cfqq->seek_history <<= 1;
Corrado Zoccolo41647e72010-02-27 19:45:40 +01003083 if (blk_queue_nonrot(cfqd->queue))
3084 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3085 else
3086 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
Jens Axboe206dc692006-03-28 13:03:44 +02003087}
Jens Axboe22e2c502005-06-27 10:55:12 +02003088
3089/*
3090 * Disable idle window if the process thinks too long or seeks so much that
3091 * it doesn't matter
3092 */
3093static void
3094cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3095 struct cfq_io_context *cic)
3096{
Jens Axboe7b679132008-05-30 12:23:07 +02003097 int old_idle, enable_idle;
Jens Axboe1be92f22007-04-19 14:32:26 +02003098
Jens Axboe08717142008-01-28 11:38:15 +01003099 /*
3100 * Don't idle for async or idle io prio class
3101 */
3102 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
Jens Axboe1be92f22007-04-19 14:32:26 +02003103 return;
3104
Jens Axboec265a7f2008-06-26 13:49:33 +02003105 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003106
Corrado Zoccolo76280af2009-11-26 10:02:58 +01003107 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3108 cfq_mark_cfqq_deep(cfqq);
3109
Nikanth Karthikesan66dac982007-11-27 12:47:04 +01003110 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
Corrado Zoccolo3dde36d2010-02-27 19:45:39 +01003111 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
Jens Axboe22e2c502005-06-27 10:55:12 +02003112 enable_idle = 0;
3113 else if (sample_valid(cic->ttime_samples)) {
Corrado Zoccolo718eee02009-10-26 22:45:29 +01003114 if (cic->ttime_mean > cfqd->cfq_slice_idle)
Jens Axboe22e2c502005-06-27 10:55:12 +02003115 enable_idle = 0;
3116 else
3117 enable_idle = 1;
3118 }
3119
Jens Axboe7b679132008-05-30 12:23:07 +02003120 if (old_idle != enable_idle) {
3121 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3122 if (enable_idle)
3123 cfq_mark_cfqq_idle_window(cfqq);
3124 else
3125 cfq_clear_cfqq_idle_window(cfqq);
3126 }
Jens Axboe22e2c502005-06-27 10:55:12 +02003127}
3128
Jens Axboe22e2c502005-06-27 10:55:12 +02003129/*
3130 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3131 * no or if we aren't sure, a 1 will cause a preempt.
3132 */
Jens Axboea6151c32009-10-07 20:02:57 +02003133static bool
Jens Axboe22e2c502005-06-27 10:55:12 +02003134cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
Jens Axboe5e705372006-07-13 12:39:25 +02003135 struct request *rq)
Jens Axboe22e2c502005-06-27 10:55:12 +02003136{
Jens Axboe6d048f52007-04-25 12:44:27 +02003137 struct cfq_queue *cfqq;
Jens Axboe22e2c502005-06-27 10:55:12 +02003138
Jens Axboe6d048f52007-04-25 12:44:27 +02003139 cfqq = cfqd->active_queue;
3140 if (!cfqq)
Jens Axboea6151c32009-10-07 20:02:57 +02003141 return false;
Jens Axboe22e2c502005-06-27 10:55:12 +02003142
Jens Axboe6d048f52007-04-25 12:44:27 +02003143 if (cfq_class_idle(new_cfqq))
Jens Axboea6151c32009-10-07 20:02:57 +02003144 return false;
Jens Axboe22e2c502005-06-27 10:55:12 +02003145
3146 if (cfq_class_idle(cfqq))
Jens Axboea6151c32009-10-07 20:02:57 +02003147 return true;
Jens Axboe1e3335d2007-02-14 19:59:49 +01003148
Jens Axboe22e2c502005-06-27 10:55:12 +02003149 /*
Divyesh Shah875feb62010-01-06 18:58:20 -08003150 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3151 */
3152 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3153 return false;
3154
3155 /*
Jens Axboe374f84a2006-07-23 01:42:19 +02003156 * if the new request is sync, but the currently running queue is
3157 * not, let the sync request have priority.
3158 */
Jens Axboe5e705372006-07-13 12:39:25 +02003159 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
Jens Axboea6151c32009-10-07 20:02:57 +02003160 return true;
Jens Axboe1e3335d2007-02-14 19:59:49 +01003161
Vivek Goyal8682e1f2009-12-03 12:59:50 -05003162 if (new_cfqq->cfqg != cfqq->cfqg)
3163 return false;
3164
3165 if (cfq_slice_used(cfqq))
3166 return true;
3167
3168 /* Allow preemption only if we are idling on sync-noidle tree */
3169 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3170 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3171 new_cfqq->service_tree->count == 2 &&
3172 RB_EMPTY_ROOT(&cfqq->sort_list))
3173 return true;
3174
Jens Axboe374f84a2006-07-23 01:42:19 +02003175 /*
3176 * So both queues are sync. Let the new request get disk time if
3177 * it's a metadata request and the current queue is doing regular IO.
3178 */
3179 if (rq_is_meta(rq) && !cfqq->meta_pending)
Jens Axboee6ec4fe2009-11-03 20:21:35 +01003180 return true;
Jens Axboe22e2c502005-06-27 10:55:12 +02003181
Divyesh Shah3a9a3f62009-01-30 12:46:41 +01003182 /*
3183 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3184 */
3185 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
Jens Axboea6151c32009-10-07 20:02:57 +02003186 return true;
Divyesh Shah3a9a3f62009-01-30 12:46:41 +01003187
Jens Axboe1e3335d2007-02-14 19:59:49 +01003188 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
Jens Axboea6151c32009-10-07 20:02:57 +02003189 return false;
Jens Axboe1e3335d2007-02-14 19:59:49 +01003190
3191 /*
3192 * if this request is as-good as one we would expect from the
3193 * current cfqq, let it preempt
3194 */
Shaohua Lie9ce3352010-03-19 08:03:04 +01003195 if (cfq_rq_close(cfqd, cfqq, rq))
Jens Axboea6151c32009-10-07 20:02:57 +02003196 return true;
Jens Axboe1e3335d2007-02-14 19:59:49 +01003197
Jens Axboea6151c32009-10-07 20:02:57 +02003198 return false;
Jens Axboe22e2c502005-06-27 10:55:12 +02003199}
3200
3201/*
3202 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3203 * let it have half of its nominal slice.
3204 */
3205static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3206{
Jens Axboe7b679132008-05-30 12:23:07 +02003207 cfq_log_cfqq(cfqd, cfqq, "preempt");
Vivek Goyale5ff0822010-04-26 19:25:11 +02003208 cfq_slice_expired(cfqd, 1);
Jens Axboe22e2c502005-06-27 10:55:12 +02003209
Jens Axboebf572252006-07-19 20:29:12 +02003210 /*
3211 * Put the new queue at the front of the of the current list,
3212 * so we know that it will be selected next.
3213 */
3214 BUG_ON(!cfq_cfqq_on_rr(cfqq));
Jens Axboeedd75ff2007-04-19 12:03:34 +02003215
3216 cfq_service_tree_add(cfqd, cfqq, 1);
Jens Axboebf572252006-07-19 20:29:12 +02003217
Jens Axboe44f7c162007-01-19 11:51:58 +11003218 cfqq->slice_end = 0;
3219 cfq_mark_cfqq_slice_new(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003220}
3221
3222/*
Jens Axboe5e705372006-07-13 12:39:25 +02003223 * Called when a new fs request (rq) is added (to cfqq). Check if there's
Jens Axboe22e2c502005-06-27 10:55:12 +02003224 * something we should do about it
3225 */
3226static void
Jens Axboe5e705372006-07-13 12:39:25 +02003227cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3228 struct request *rq)
Jens Axboe22e2c502005-06-27 10:55:12 +02003229{
Jens Axboe5e705372006-07-13 12:39:25 +02003230 struct cfq_io_context *cic = RQ_CIC(rq);
Jens Axboe12e9fdd2006-06-01 10:09:56 +02003231
Aaron Carroll45333d52008-08-26 15:52:36 +02003232 cfqd->rq_queued++;
Jens Axboe374f84a2006-07-23 01:42:19 +02003233 if (rq_is_meta(rq))
3234 cfqq->meta_pending++;
3235
Jens Axboe9c2c38a2005-08-24 14:57:54 +02003236 cfq_update_io_thinktime(cfqd, cic);
Jeff Moyerb2c18e12009-10-23 17:14:49 -04003237 cfq_update_io_seektime(cfqd, cfqq, rq);
Jens Axboe9c2c38a2005-08-24 14:57:54 +02003238 cfq_update_idle_window(cfqd, cfqq, cic);
3239
Jeff Moyerb2c18e12009-10-23 17:14:49 -04003240 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003241
3242 if (cfqq == cfqd->active_queue) {
3243 /*
Jens Axboeb0291952009-04-07 11:38:31 +02003244 * Remember that we saw a request from this process, but
3245 * don't start queuing just yet. Otherwise we risk seeing lots
3246 * of tiny requests, because we disrupt the normal plugging
Jens Axboed6ceb252009-04-14 14:18:16 +02003247 * and merging. If the request is already larger than a single
3248 * page, let it rip immediately. For that case we assume that
Jens Axboe2d870722009-04-15 12:12:46 +02003249 * merging is already done. Ditto for a busy system that
3250 * has other work pending, don't risk delaying until the
3251 * idle timer unplug to continue working.
Jens Axboe22e2c502005-06-27 10:55:12 +02003252 */
Jens Axboed6ceb252009-04-14 14:18:16 +02003253 if (cfq_cfqq_wait_request(cfqq)) {
Jens Axboe2d870722009-04-15 12:12:46 +02003254 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3255 cfqd->busy_queues > 1) {
Divyesh Shah812df482010-04-08 21:15:35 -07003256 cfq_del_timer(cfqd, cfqq);
Gui Jianfeng554554f2009-12-10 09:38:39 +01003257 cfq_clear_cfqq_wait_request(cfqq);
Vivek Goyalbf791932009-12-03 12:59:37 -05003258 __blk_run_queue(cfqd->queue);
Divyesh Shaha11cdaa2010-04-13 19:59:17 +02003259 } else {
Vivek Goyale98ef892010-06-18 10:39:47 -04003260 cfq_blkiocg_update_idle_time_stats(
Divyesh Shaha11cdaa2010-04-13 19:59:17 +02003261 &cfqq->cfqg->blkg);
Vivek Goyalbf791932009-12-03 12:59:37 -05003262 cfq_mark_cfqq_must_dispatch(cfqq);
Divyesh Shaha11cdaa2010-04-13 19:59:17 +02003263 }
Jens Axboed6ceb252009-04-14 14:18:16 +02003264 }
Jens Axboe5e705372006-07-13 12:39:25 +02003265 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
Jens Axboe22e2c502005-06-27 10:55:12 +02003266 /*
3267 * not the active queue - expire current slice if it is
3268 * idle and has expired it's mean thinktime or this new queue
Divyesh Shah3a9a3f62009-01-30 12:46:41 +01003269 * has some old slice time left and is of higher priority or
3270 * this new queue is RT and the current one is BE
Jens Axboe22e2c502005-06-27 10:55:12 +02003271 */
3272 cfq_preempt_queue(cfqd, cfqq);
Tejun Heoa7f55792009-04-23 11:05:17 +09003273 __blk_run_queue(cfqd->queue);
Jens Axboe22e2c502005-06-27 10:55:12 +02003274 }
3275}
3276
Jens Axboe165125e2007-07-24 09:28:11 +02003277static void cfq_insert_request(struct request_queue *q, struct request *rq)
Jens Axboe22e2c502005-06-27 10:55:12 +02003278{
Jens Axboeb4878f22005-10-20 16:42:29 +02003279 struct cfq_data *cfqd = q->elevator->elevator_data;
Jens Axboe5e705372006-07-13 12:39:25 +02003280 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003281
Jens Axboe7b679132008-05-30 12:23:07 +02003282 cfq_log_cfqq(cfqd, cfqq, "insert_request");
Jens Axboefd0928d2008-01-24 08:52:45 +01003283 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003284
Jens Axboe30996f42009-10-05 11:03:39 +02003285 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
Jens Axboe22e2c502005-06-27 10:55:12 +02003286 list_add_tail(&rq->queuelist, &cfqq->fifo);
Corrado Zoccoloaa6f6a32009-10-26 22:44:33 +01003287 cfq_add_rq_rb(rq);
Vivek Goyale98ef892010-06-18 10:39:47 -04003288 cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
Divyesh Shahcdc11842010-04-08 21:15:10 -07003289 &cfqd->serving_group->blkg, rq_data_dir(rq),
3290 rq_is_sync(rq));
Jens Axboe5e705372006-07-13 12:39:25 +02003291 cfq_rq_enqueued(cfqd, cfqq, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003292}
3293
Aaron Carroll45333d52008-08-26 15:52:36 +02003294/*
3295 * Update hw_tag based on peak queue depth over 50 samples under
3296 * sufficient load.
3297 */
3298static void cfq_update_hw_tag(struct cfq_data *cfqd)
3299{
Shaohua Li1a1238a2009-10-27 08:46:23 +01003300 struct cfq_queue *cfqq = cfqd->active_queue;
3301
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003302 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3303 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
Corrado Zoccoloe459dd02009-11-26 10:02:57 +01003304
3305 if (cfqd->hw_tag == 1)
3306 return;
Aaron Carroll45333d52008-08-26 15:52:36 +02003307
3308 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003309 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
Aaron Carroll45333d52008-08-26 15:52:36 +02003310 return;
3311
Shaohua Li1a1238a2009-10-27 08:46:23 +01003312 /*
3313 * If active queue hasn't enough requests and can idle, cfq might not
3314 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3315 * case
3316 */
3317 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3318 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003319 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
Shaohua Li1a1238a2009-10-27 08:46:23 +01003320 return;
3321
Aaron Carroll45333d52008-08-26 15:52:36 +02003322 if (cfqd->hw_tag_samples++ < 50)
3323 return;
3324
Corrado Zoccoloe459dd02009-11-26 10:02:57 +01003325 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
Aaron Carroll45333d52008-08-26 15:52:36 +02003326 cfqd->hw_tag = 1;
3327 else
3328 cfqd->hw_tag = 0;
Aaron Carroll45333d52008-08-26 15:52:36 +02003329}
3330
Vivek Goyal7667aa02009-12-08 17:52:58 -05003331static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3332{
3333 struct cfq_io_context *cic = cfqd->active_cic;
3334
3335 /* If there are other queues in the group, don't wait */
3336 if (cfqq->cfqg->nr_cfqq > 1)
3337 return false;
3338
3339 if (cfq_slice_used(cfqq))
3340 return true;
3341
3342 /* if slice left is less than think time, wait busy */
3343 if (cic && sample_valid(cic->ttime_samples)
3344 && (cfqq->slice_end - jiffies < cic->ttime_mean))
3345 return true;
3346
3347 /*
3348 * If think times is less than a jiffy than ttime_mean=0 and above
3349 * will not be true. It might happen that slice has not expired yet
3350 * but will expire soon (4-5 ns) during select_queue(). To cover the
3351 * case where think time is less than a jiffy, mark the queue wait
3352 * busy if only 1 jiffy is left in the slice.
3353 */
3354 if (cfqq->slice_end - jiffies == 1)
3355 return true;
3356
3357 return false;
3358}
3359
Jens Axboe165125e2007-07-24 09:28:11 +02003360static void cfq_completed_request(struct request_queue *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003361{
Jens Axboe5e705372006-07-13 12:39:25 +02003362 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Jens Axboeb4878f22005-10-20 16:42:29 +02003363 struct cfq_data *cfqd = cfqq->cfqd;
Jens Axboe5380a102006-07-13 12:37:56 +02003364 const int sync = rq_is_sync(rq);
Jens Axboeb4878f22005-10-20 16:42:29 +02003365 unsigned long now;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003366
Jens Axboeb4878f22005-10-20 16:42:29 +02003367 now = jiffies;
Vivek Goyal2868ef72009-12-03 12:59:48 -05003368 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", !!rq_noidle(rq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003369
Aaron Carroll45333d52008-08-26 15:52:36 +02003370 cfq_update_hw_tag(cfqd);
3371
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003372 WARN_ON(!cfqd->rq_in_driver);
Jens Axboe6d048f52007-04-25 12:44:27 +02003373 WARN_ON(!cfqq->dispatched);
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003374 cfqd->rq_in_driver--;
Jens Axboe6d048f52007-04-25 12:44:27 +02003375 cfqq->dispatched--;
Vivek Goyale98ef892010-06-18 10:39:47 -04003376 cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
3377 rq_start_time_ns(rq), rq_io_start_time_ns(rq),
3378 rq_data_dir(rq), rq_is_sync(rq));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003379
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003380 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
Jens Axboe3ed9a292007-04-23 08:33:33 +02003381
Vivek Goyal365722b2009-10-03 15:21:27 +02003382 if (sync) {
Jens Axboe5e705372006-07-13 12:39:25 +02003383 RQ_CIC(rq)->last_end_request = now;
Corrado Zoccolo573412b2009-12-06 11:48:52 +01003384 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3385 cfqd->last_delayed_sync = now;
Vivek Goyal365722b2009-10-03 15:21:27 +02003386 }
Jens Axboecaaa5f92006-06-16 11:23:00 +02003387
3388 /*
3389 * If this is the active queue, check if it needs to be expired,
3390 * or if we want to idle in case it has no pending requests.
3391 */
3392 if (cfqd->active_queue == cfqq) {
Jens Axboea36e71f2009-04-15 12:15:11 +02003393 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3394
Jens Axboe44f7c162007-01-19 11:51:58 +11003395 if (cfq_cfqq_slice_new(cfqq)) {
3396 cfq_set_prio_slice(cfqd, cfqq);
3397 cfq_clear_cfqq_slice_new(cfqq);
3398 }
Vivek Goyalf75edf22009-12-03 12:59:53 -05003399
3400 /*
Vivek Goyal7667aa02009-12-08 17:52:58 -05003401 * Should we wait for next request to come in before we expire
3402 * the queue.
Vivek Goyalf75edf22009-12-03 12:59:53 -05003403 */
Vivek Goyal7667aa02009-12-08 17:52:58 -05003404 if (cfq_should_wait_busy(cfqd, cfqq)) {
Vivek Goyalf75edf22009-12-03 12:59:53 -05003405 cfqq->slice_end = jiffies + cfqd->cfq_slice_idle;
3406 cfq_mark_cfqq_wait_busy(cfqq);
Divyesh Shahb1ffe732010-03-25 15:45:03 +01003407 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
Vivek Goyalf75edf22009-12-03 12:59:53 -05003408 }
3409
Jens Axboea36e71f2009-04-15 12:15:11 +02003410 /*
Corrado Zoccolo8e550632009-11-26 10:02:58 +01003411 * Idling is not enabled on:
3412 * - expired queues
3413 * - idle-priority queues
3414 * - async queues
3415 * - queues with still some requests queued
3416 * - when there is a close cooperator
Jens Axboea36e71f2009-04-15 12:15:11 +02003417 */
Jens Axboe08717142008-01-28 11:38:15 +01003418 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
Vivek Goyale5ff0822010-04-26 19:25:11 +02003419 cfq_slice_expired(cfqd, 1);
Corrado Zoccolo8e550632009-11-26 10:02:58 +01003420 else if (sync && cfqq_empty &&
3421 !cfq_close_cooperator(cfqd, cfqq)) {
3422 cfqd->noidle_tree_requires_idle |= !rq_noidle(rq);
3423 /*
3424 * Idling is enabled for SYNC_WORKLOAD.
3425 * SYNC_NOIDLE_WORKLOAD idles at the end of the tree
3426 * only if we processed at least one !rq_noidle request
3427 */
3428 if (cfqd->serving_type == SYNC_WORKLOAD
Vivek Goyalc04645e2009-12-03 12:59:56 -05003429 || cfqd->noidle_tree_requires_idle
3430 || cfqq->cfqg->nr_cfqq == 1)
Corrado Zoccolo8e550632009-11-26 10:02:58 +01003431 cfq_arm_slice_timer(cfqd);
3432 }
Jens Axboecaaa5f92006-06-16 11:23:00 +02003433 }
Jens Axboe6d048f52007-04-25 12:44:27 +02003434
Corrado Zoccolo53c583d2010-02-28 19:45:05 +01003435 if (!cfqd->rq_in_driver)
Jens Axboe23e018a2009-10-05 08:52:35 +02003436 cfq_schedule_dispatch(cfqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003437}
3438
Jens Axboe22e2c502005-06-27 10:55:12 +02003439/*
3440 * we temporarily boost lower priority queues if they are holding fs exclusive
3441 * resources. they are boosted to normal prio (CLASS_BE/4)
3442 */
3443static void cfq_prio_boost(struct cfq_queue *cfqq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003444{
Jens Axboe22e2c502005-06-27 10:55:12 +02003445 if (has_fs_excl()) {
3446 /*
3447 * boost idle prio on transactions that would lock out other
3448 * users of the filesystem
3449 */
3450 if (cfq_class_idle(cfqq))
3451 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3452 if (cfqq->ioprio > IOPRIO_NORM)
3453 cfqq->ioprio = IOPRIO_NORM;
3454 } else {
3455 /*
Corrado Zoccolodddb7452009-11-02 10:40:37 +01003456 * unboost the queue (if needed)
Jens Axboe22e2c502005-06-27 10:55:12 +02003457 */
Corrado Zoccolodddb7452009-11-02 10:40:37 +01003458 cfqq->ioprio_class = cfqq->org_ioprio_class;
3459 cfqq->ioprio = cfqq->org_ioprio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003460 }
Jens Axboe22e2c502005-06-27 10:55:12 +02003461}
3462
Jens Axboe89850f72006-07-22 16:48:31 +02003463static inline int __cfq_may_queue(struct cfq_queue *cfqq)
Jens Axboe22e2c502005-06-27 10:55:12 +02003464{
Jens Axboe1b379d82009-08-11 08:26:11 +02003465 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
Jens Axboe3b181522005-06-27 10:56:24 +02003466 cfq_mark_cfqq_must_alloc_slice(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003467 return ELV_MQUEUE_MUST;
Jens Axboe3b181522005-06-27 10:56:24 +02003468 }
Jens Axboe22e2c502005-06-27 10:55:12 +02003469
3470 return ELV_MQUEUE_MAY;
Jens Axboe22e2c502005-06-27 10:55:12 +02003471}
3472
Jens Axboe165125e2007-07-24 09:28:11 +02003473static int cfq_may_queue(struct request_queue *q, int rw)
Jens Axboe22e2c502005-06-27 10:55:12 +02003474{
3475 struct cfq_data *cfqd = q->elevator->elevator_data;
3476 struct task_struct *tsk = current;
Vasily Tarasov91fac312007-04-25 12:29:51 +02003477 struct cfq_io_context *cic;
Jens Axboe22e2c502005-06-27 10:55:12 +02003478 struct cfq_queue *cfqq;
3479
3480 /*
3481 * don't force setup of a queue from here, as a call to may_queue
3482 * does not necessarily imply that a request actually will be queued.
3483 * so just lookup a possibly existing queue, or return 'may queue'
3484 * if that fails
3485 */
Jens Axboe4ac845a2008-01-24 08:44:49 +01003486 cic = cfq_cic_lookup(cfqd, tsk->io_context);
Vasily Tarasov91fac312007-04-25 12:29:51 +02003487 if (!cic)
3488 return ELV_MQUEUE_MAY;
3489
Jens Axboeb0b78f82009-04-08 10:56:08 +02003490 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
Jens Axboe22e2c502005-06-27 10:55:12 +02003491 if (cfqq) {
Jens Axboefd0928d2008-01-24 08:52:45 +01003492 cfq_init_prio_data(cfqq, cic->ioc);
Jens Axboe22e2c502005-06-27 10:55:12 +02003493 cfq_prio_boost(cfqq);
3494
Jens Axboe89850f72006-07-22 16:48:31 +02003495 return __cfq_may_queue(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003496 }
3497
3498 return ELV_MQUEUE_MAY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003499}
3500
Linus Torvalds1da177e2005-04-16 15:20:36 -07003501/*
3502 * queue lock held here
3503 */
Jens Axboebb37b942006-12-01 10:42:33 +01003504static void cfq_put_request(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003505{
Jens Axboe5e705372006-07-13 12:39:25 +02003506 struct cfq_queue *cfqq = RQ_CFQQ(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003507
Jens Axboe5e705372006-07-13 12:39:25 +02003508 if (cfqq) {
Jens Axboe22e2c502005-06-27 10:55:12 +02003509 const int rw = rq_data_dir(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003510
Jens Axboe22e2c502005-06-27 10:55:12 +02003511 BUG_ON(!cfqq->allocated[rw]);
3512 cfqq->allocated[rw]--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003513
Jens Axboe5e705372006-07-13 12:39:25 +02003514 put_io_context(RQ_CIC(rq)->ioc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003515
Linus Torvalds1da177e2005-04-16 15:20:36 -07003516 rq->elevator_private = NULL;
Jens Axboe5e705372006-07-13 12:39:25 +02003517 rq->elevator_private2 = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003518
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02003519 /* Put down rq reference on cfqg */
3520 cfq_put_cfqg(RQ_CFQG(rq));
3521 rq->elevator_private3 = NULL;
3522
Linus Torvalds1da177e2005-04-16 15:20:36 -07003523 cfq_put_queue(cfqq);
3524 }
3525}
3526
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04003527static struct cfq_queue *
3528cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3529 struct cfq_queue *cfqq)
3530{
3531 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3532 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
Jeff Moyerb3b6d042009-10-23 17:14:51 -04003533 cfq_mark_cfqq_coop(cfqq->new_cfqq);
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04003534 cfq_put_queue(cfqq);
3535 return cic_to_cfqq(cic, 1);
3536}
3537
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003538/*
3539 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3540 * was the last process referring to said cfqq.
3541 */
3542static struct cfq_queue *
3543split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3544{
3545 if (cfqq_process_refs(cfqq) == 1) {
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003546 cfqq->pid = current->pid;
3547 cfq_clear_cfqq_coop(cfqq);
Shaohua Liae54abe2010-02-05 13:11:45 +01003548 cfq_clear_cfqq_split_coop(cfqq);
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003549 return cfqq;
3550 }
3551
3552 cic_set_cfqq(cic, NULL, 1);
Shaohua Lid02a2c02010-05-25 10:16:53 +02003553
3554 cfq_put_cooperator(cfqq);
3555
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003556 cfq_put_queue(cfqq);
3557 return NULL;
3558}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003559/*
Jens Axboe22e2c502005-06-27 10:55:12 +02003560 * Allocate cfq data structures associated with this request.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003561 */
Jens Axboe22e2c502005-06-27 10:55:12 +02003562static int
Jens Axboe165125e2007-07-24 09:28:11 +02003563cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003564{
3565 struct cfq_data *cfqd = q->elevator->elevator_data;
3566 struct cfq_io_context *cic;
3567 const int rw = rq_data_dir(rq);
Jens Axboea6151c32009-10-07 20:02:57 +02003568 const bool is_sync = rq_is_sync(rq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003569 struct cfq_queue *cfqq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003570 unsigned long flags;
3571
3572 might_sleep_if(gfp_mask & __GFP_WAIT);
3573
Jens Axboee2d74ac2006-03-28 08:59:01 +02003574 cic = cfq_get_io_context(cfqd, gfp_mask);
Jens Axboe22e2c502005-06-27 10:55:12 +02003575
Linus Torvalds1da177e2005-04-16 15:20:36 -07003576 spin_lock_irqsave(q->queue_lock, flags);
3577
Jens Axboe22e2c502005-06-27 10:55:12 +02003578 if (!cic)
3579 goto queue_fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003580
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003581new_queue:
Vasily Tarasov91fac312007-04-25 12:29:51 +02003582 cfqq = cic_to_cfqq(cic, is_sync);
Vivek Goyal32f2e802009-07-09 22:13:16 +02003583 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
Jens Axboefd0928d2008-01-24 08:52:45 +01003584 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
Vasily Tarasov91fac312007-04-25 12:29:51 +02003585 cic_set_cfqq(cic, cfqq, is_sync);
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04003586 } else {
3587 /*
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003588 * If the queue was seeky for too long, break it apart.
3589 */
Shaohua Liae54abe2010-02-05 13:11:45 +01003590 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
Jeff Moyere6c5bc72009-10-23 17:14:52 -04003591 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3592 cfqq = split_cfqq(cic, cfqq);
3593 if (!cfqq)
3594 goto new_queue;
3595 }
3596
3597 /*
Jeff Moyerdf5fe3e2009-10-23 17:14:50 -04003598 * Check to see if this queue is scheduled to merge with
3599 * another, closely cooperating queue. The merging of
3600 * queues happens here as it must be done in process context.
3601 * The reference on new_cfqq was taken in merge_cfqqs.
3602 */
3603 if (cfqq->new_cfqq)
3604 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
Vasily Tarasov91fac312007-04-25 12:29:51 +02003605 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003606
3607 cfqq->allocated[rw]++;
Jens Axboe22e2c502005-06-27 10:55:12 +02003608 atomic_inc(&cfqq->ref);
Jens Axboe5e705372006-07-13 12:39:25 +02003609
Linus Torvalds1da177e2005-04-16 15:20:36 -07003610 spin_unlock_irqrestore(q->queue_lock, flags);
3611
Jens Axboe5e705372006-07-13 12:39:25 +02003612 rq->elevator_private = cic;
3613 rq->elevator_private2 = cfqq;
Vivek Goyal7f1dc8a2010-04-21 17:44:16 +02003614 rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg);
Jens Axboe5e705372006-07-13 12:39:25 +02003615 return 0;
Jens Axboe3b181522005-06-27 10:56:24 +02003616
Jens Axboe22e2c502005-06-27 10:55:12 +02003617queue_fail:
3618 if (cic)
3619 put_io_context(cic->ioc);
Jens Axboe89850f72006-07-22 16:48:31 +02003620
Jens Axboe23e018a2009-10-05 08:52:35 +02003621 cfq_schedule_dispatch(cfqd);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003622 spin_unlock_irqrestore(q->queue_lock, flags);
Jens Axboe7b679132008-05-30 12:23:07 +02003623 cfq_log(cfqd, "set_request fail");
Linus Torvalds1da177e2005-04-16 15:20:36 -07003624 return 1;
3625}
3626
David Howells65f27f32006-11-22 14:55:48 +00003627static void cfq_kick_queue(struct work_struct *work)
Jens Axboe22e2c502005-06-27 10:55:12 +02003628{
David Howells65f27f32006-11-22 14:55:48 +00003629 struct cfq_data *cfqd =
Jens Axboe23e018a2009-10-05 08:52:35 +02003630 container_of(work, struct cfq_data, unplug_work);
Jens Axboe165125e2007-07-24 09:28:11 +02003631 struct request_queue *q = cfqd->queue;
Jens Axboe22e2c502005-06-27 10:55:12 +02003632
Jens Axboe40bb54d2009-04-15 12:11:10 +02003633 spin_lock_irq(q->queue_lock);
Tejun Heoa7f55792009-04-23 11:05:17 +09003634 __blk_run_queue(cfqd->queue);
Jens Axboe40bb54d2009-04-15 12:11:10 +02003635 spin_unlock_irq(q->queue_lock);
Jens Axboe22e2c502005-06-27 10:55:12 +02003636}
3637
3638/*
3639 * Timer running if the active_queue is currently idling inside its time slice
3640 */
3641static void cfq_idle_slice_timer(unsigned long data)
3642{
3643 struct cfq_data *cfqd = (struct cfq_data *) data;
3644 struct cfq_queue *cfqq;
3645 unsigned long flags;
Jens Axboe3c6bd2f2007-01-19 12:06:33 +11003646 int timed_out = 1;
Jens Axboe22e2c502005-06-27 10:55:12 +02003647
Jens Axboe7b679132008-05-30 12:23:07 +02003648 cfq_log(cfqd, "idle timer fired");
3649
Jens Axboe22e2c502005-06-27 10:55:12 +02003650 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3651
Jens Axboefe094d92008-01-31 13:08:54 +01003652 cfqq = cfqd->active_queue;
3653 if (cfqq) {
Jens Axboe3c6bd2f2007-01-19 12:06:33 +11003654 timed_out = 0;
3655
Jens Axboe22e2c502005-06-27 10:55:12 +02003656 /*
Jens Axboeb0291952009-04-07 11:38:31 +02003657 * We saw a request before the queue expired, let it through
3658 */
3659 if (cfq_cfqq_must_dispatch(cfqq))
3660 goto out_kick;
3661
3662 /*
Jens Axboe22e2c502005-06-27 10:55:12 +02003663 * expired
3664 */
Jens Axboe44f7c162007-01-19 11:51:58 +11003665 if (cfq_slice_used(cfqq))
Jens Axboe22e2c502005-06-27 10:55:12 +02003666 goto expire;
3667
3668 /*
3669 * only expire and reinvoke request handler, if there are
3670 * other queues with pending requests
3671 */
Jens Axboecaaa5f92006-06-16 11:23:00 +02003672 if (!cfqd->busy_queues)
Jens Axboe22e2c502005-06-27 10:55:12 +02003673 goto out_cont;
Jens Axboe22e2c502005-06-27 10:55:12 +02003674
3675 /*
3676 * not expired and it has a request pending, let it dispatch
3677 */
Jens Axboe75e50982009-04-07 08:56:14 +02003678 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
Jens Axboe22e2c502005-06-27 10:55:12 +02003679 goto out_kick;
Corrado Zoccolo76280af2009-11-26 10:02:58 +01003680
3681 /*
3682 * Queue depth flag is reset only when the idle didn't succeed
3683 */
3684 cfq_clear_cfqq_deep(cfqq);
Jens Axboe22e2c502005-06-27 10:55:12 +02003685 }
3686expire:
Vivek Goyale5ff0822010-04-26 19:25:11 +02003687 cfq_slice_expired(cfqd, timed_out);
Jens Axboe22e2c502005-06-27 10:55:12 +02003688out_kick:
Jens Axboe23e018a2009-10-05 08:52:35 +02003689 cfq_schedule_dispatch(cfqd);
Jens Axboe22e2c502005-06-27 10:55:12 +02003690out_cont:
3691 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3692}
3693
Jens Axboe3b181522005-06-27 10:56:24 +02003694static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3695{
3696 del_timer_sync(&cfqd->idle_slice_timer);
Jens Axboe23e018a2009-10-05 08:52:35 +02003697 cancel_work_sync(&cfqd->unplug_work);
Jens Axboe3b181522005-06-27 10:56:24 +02003698}
Jens Axboe22e2c502005-06-27 10:55:12 +02003699
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02003700static void cfq_put_async_queues(struct cfq_data *cfqd)
3701{
3702 int i;
3703
3704 for (i = 0; i < IOPRIO_BE_NR; i++) {
3705 if (cfqd->async_cfqq[0][i])
3706 cfq_put_queue(cfqd->async_cfqq[0][i]);
3707 if (cfqd->async_cfqq[1][i])
3708 cfq_put_queue(cfqd->async_cfqq[1][i]);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02003709 }
Oleg Nesterov2389d1e2007-11-05 08:58:05 +01003710
3711 if (cfqd->async_idle_cfqq)
3712 cfq_put_queue(cfqd->async_idle_cfqq);
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02003713}
3714
Jens Axboebb729bc2009-12-06 09:54:19 +01003715static void cfq_cfqd_free(struct rcu_head *head)
3716{
3717 kfree(container_of(head, struct cfq_data, rcu));
3718}
3719
Jens Axboeb374d182008-10-31 10:05:07 +01003720static void cfq_exit_queue(struct elevator_queue *e)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003721{
Jens Axboe22e2c502005-06-27 10:55:12 +02003722 struct cfq_data *cfqd = e->elevator_data;
Jens Axboe165125e2007-07-24 09:28:11 +02003723 struct request_queue *q = cfqd->queue;
Jens Axboe22e2c502005-06-27 10:55:12 +02003724
Jens Axboe3b181522005-06-27 10:56:24 +02003725 cfq_shutdown_timer_wq(cfqd);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003726
Al Virod9ff4182006-03-18 13:51:22 -05003727 spin_lock_irq(q->queue_lock);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003728
Al Virod9ff4182006-03-18 13:51:22 -05003729 if (cfqd->active_queue)
Vivek Goyale5ff0822010-04-26 19:25:11 +02003730 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003731
3732 while (!list_empty(&cfqd->cic_list)) {
Al Virod9ff4182006-03-18 13:51:22 -05003733 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3734 struct cfq_io_context,
3735 queue_list);
Jens Axboe89850f72006-07-22 16:48:31 +02003736
3737 __cfq_exit_single_io_context(cfqd, cic);
Al Virod9ff4182006-03-18 13:51:22 -05003738 }
Jens Axboee2d74ac2006-03-28 08:59:01 +02003739
Vasily Tarasovc2dea2d2007-07-20 10:06:38 +02003740 cfq_put_async_queues(cfqd);
Vivek Goyalb1c35762009-12-03 12:59:47 -05003741 cfq_release_cfq_groups(cfqd);
Vivek Goyale98ef892010-06-18 10:39:47 -04003742 cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
Jens Axboe15c31be2007-07-10 13:43:25 +02003743
Al Virod9ff4182006-03-18 13:51:22 -05003744 spin_unlock_irq(q->queue_lock);
Al Viroa90d7422006-03-18 12:05:37 -05003745
3746 cfq_shutdown_timer_wq(cfqd);
3747
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +04003748 spin_lock(&cic_index_lock);
3749 ida_remove(&cic_index_ida, cfqd->cic_index);
3750 spin_unlock(&cic_index_lock);
3751
Vivek Goyalb1c35762009-12-03 12:59:47 -05003752 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
Jens Axboebb729bc2009-12-06 09:54:19 +01003753 call_rcu(&cfqd->rcu, cfq_cfqd_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003754}
3755
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +04003756static int cfq_alloc_cic_index(void)
3757{
3758 int index, error;
3759
3760 do {
3761 if (!ida_pre_get(&cic_index_ida, GFP_KERNEL))
3762 return -ENOMEM;
3763
3764 spin_lock(&cic_index_lock);
3765 error = ida_get_new(&cic_index_ida, &index);
3766 spin_unlock(&cic_index_lock);
3767 if (error && error != -EAGAIN)
3768 return error;
3769 } while (error);
3770
3771 return index;
3772}
3773
Jens Axboe165125e2007-07-24 09:28:11 +02003774static void *cfq_init_queue(struct request_queue *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003775{
3776 struct cfq_data *cfqd;
Corrado Zoccolo718eee02009-10-26 22:45:29 +01003777 int i, j;
Vivek Goyalcdb16e82009-12-03 12:59:38 -05003778 struct cfq_group *cfqg;
Vivek Goyal615f0252009-12-03 12:59:39 -05003779 struct cfq_rb_root *st;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003780
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +04003781 i = cfq_alloc_cic_index();
3782 if (i < 0)
3783 return NULL;
3784
Christoph Lameter94f60302007-07-17 04:03:29 -07003785 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003786 if (!cfqd)
Jens Axboebc1c1162006-06-08 08:49:06 +02003787 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003788
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +04003789 cfqd->cic_index = i;
3790
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05003791 /* Init root service tree */
3792 cfqd->grp_service_tree = CFQ_RB_ROOT;
3793
Vivek Goyalcdb16e82009-12-03 12:59:38 -05003794 /* Init root group */
3795 cfqg = &cfqd->root_group;
Vivek Goyal615f0252009-12-03 12:59:39 -05003796 for_each_cfqg_st(cfqg, i, j, st)
3797 *st = CFQ_RB_ROOT;
Vivek Goyal1fa8f6d2009-12-03 12:59:41 -05003798 RB_CLEAR_NODE(&cfqg->rb_node);
Jens Axboe26a2ac02009-04-23 12:13:27 +02003799
Vivek Goyal25bc6b02009-12-03 12:59:43 -05003800 /* Give preference to root group over other groups */
3801 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3802
Vivek Goyal25fb5162009-12-03 12:59:46 -05003803#ifdef CONFIG_CFQ_GROUP_IOSCHED
Vivek Goyalb1c35762009-12-03 12:59:47 -05003804 /*
3805 * Take a reference to root group which we never drop. This is just
3806 * to make sure that cfq_put_cfqg() does not try to kfree root group
3807 */
3808 atomic_set(&cfqg->ref, 1);
Vivek Goyaldcf097b2010-04-22 11:54:52 -04003809 rcu_read_lock();
Vivek Goyale98ef892010-06-18 10:39:47 -04003810 cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
3811 (void *)cfqd, 0);
Vivek Goyaldcf097b2010-04-22 11:54:52 -04003812 rcu_read_unlock();
Vivek Goyal25fb5162009-12-03 12:59:46 -05003813#endif
Jens Axboe26a2ac02009-04-23 12:13:27 +02003814 /*
3815 * Not strictly needed (since RB_ROOT just clears the node and we
3816 * zeroed cfqd on alloc), but better be safe in case someone decides
3817 * to add magic to the rb code
3818 */
3819 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3820 cfqd->prio_trees[i] = RB_ROOT;
3821
Jens Axboe6118b702009-06-30 09:34:12 +02003822 /*
3823 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3824 * Grab a permanent reference to it, so that the normal code flow
3825 * will not attempt to free it.
3826 */
3827 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3828 atomic_inc(&cfqd->oom_cfqq.ref);
Vivek Goyalcdb16e82009-12-03 12:59:38 -05003829 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
Jens Axboe6118b702009-06-30 09:34:12 +02003830
Al Virod9ff4182006-03-18 13:51:22 -05003831 INIT_LIST_HEAD(&cfqd->cic_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003832
Linus Torvalds1da177e2005-04-16 15:20:36 -07003833 cfqd->queue = q;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003834
Jens Axboe22e2c502005-06-27 10:55:12 +02003835 init_timer(&cfqd->idle_slice_timer);
3836 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3837 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3838
Jens Axboe23e018a2009-10-05 08:52:35 +02003839 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
Jens Axboe22e2c502005-06-27 10:55:12 +02003840
Linus Torvalds1da177e2005-04-16 15:20:36 -07003841 cfqd->cfq_quantum = cfq_quantum;
Jens Axboe22e2c502005-06-27 10:55:12 +02003842 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3843 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
Linus Torvalds1da177e2005-04-16 15:20:36 -07003844 cfqd->cfq_back_max = cfq_back_max;
3845 cfqd->cfq_back_penalty = cfq_back_penalty;
Jens Axboe22e2c502005-06-27 10:55:12 +02003846 cfqd->cfq_slice[0] = cfq_slice_async;
3847 cfqd->cfq_slice[1] = cfq_slice_sync;
3848 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3849 cfqd->cfq_slice_idle = cfq_slice_idle;
Jens Axboe963b72f2009-10-03 19:42:18 +02003850 cfqd->cfq_latency = 1;
Vivek Goyalae30c282009-12-03 12:59:55 -05003851 cfqd->cfq_group_isolation = 0;
Corrado Zoccoloe459dd02009-11-26 10:02:57 +01003852 cfqd->hw_tag = -1;
Corrado Zoccoloedc71132009-12-09 20:56:04 +01003853 /*
3854 * we optimistically start assuming sync ops weren't delayed in last
3855 * second, in order to have larger depth for async operations.
3856 */
Corrado Zoccolo573412b2009-12-06 11:48:52 +01003857 cfqd->last_delayed_sync = jiffies - HZ;
Jens Axboebc1c1162006-06-08 08:49:06 +02003858 return cfqd;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003859}
3860
3861static void cfq_slab_kill(void)
3862{
Jens Axboed6de8be2008-05-28 14:46:59 +02003863 /*
3864 * Caller already ensured that pending RCU callbacks are completed,
3865 * so we should have no busy allocations at this point.
3866 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003867 if (cfq_pool)
3868 kmem_cache_destroy(cfq_pool);
3869 if (cfq_ioc_pool)
3870 kmem_cache_destroy(cfq_ioc_pool);
3871}
3872
3873static int __init cfq_slab_setup(void)
3874{
Christoph Lameter0a31bd52007-05-06 14:49:57 -07003875 cfq_pool = KMEM_CACHE(cfq_queue, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003876 if (!cfq_pool)
3877 goto fail;
3878
Fabio Checconi34e6bbf2008-04-02 14:31:02 +02003879 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003880 if (!cfq_ioc_pool)
3881 goto fail;
3882
3883 return 0;
3884fail:
3885 cfq_slab_kill();
3886 return -ENOMEM;
3887}
3888
Linus Torvalds1da177e2005-04-16 15:20:36 -07003889/*
3890 * sysfs parts below -->
3891 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003892static ssize_t
3893cfq_var_show(unsigned int var, char *page)
3894{
3895 return sprintf(page, "%d\n", var);
3896}
3897
3898static ssize_t
3899cfq_var_store(unsigned int *var, const char *page, size_t count)
3900{
3901 char *p = (char *) page;
3902
3903 *var = simple_strtoul(p, &p, 10);
3904 return count;
3905}
3906
Linus Torvalds1da177e2005-04-16 15:20:36 -07003907#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
Jens Axboeb374d182008-10-31 10:05:07 +01003908static ssize_t __FUNC(struct elevator_queue *e, char *page) \
Linus Torvalds1da177e2005-04-16 15:20:36 -07003909{ \
Al Viro3d1ab402006-03-18 18:35:43 -05003910 struct cfq_data *cfqd = e->elevator_data; \
Linus Torvalds1da177e2005-04-16 15:20:36 -07003911 unsigned int __data = __VAR; \
3912 if (__CONV) \
3913 __data = jiffies_to_msecs(__data); \
3914 return cfq_var_show(__data, (page)); \
3915}
3916SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
Jens Axboe22e2c502005-06-27 10:55:12 +02003917SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
3918SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
Al Viroe572ec72006-03-18 22:27:18 -05003919SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
3920SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
Jens Axboe22e2c502005-06-27 10:55:12 +02003921SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
3922SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
3923SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
3924SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
Jens Axboe963b72f2009-10-03 19:42:18 +02003925SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
Vivek Goyalae30c282009-12-03 12:59:55 -05003926SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003927#undef SHOW_FUNCTION
3928
3929#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
Jens Axboeb374d182008-10-31 10:05:07 +01003930static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
Linus Torvalds1da177e2005-04-16 15:20:36 -07003931{ \
Al Viro3d1ab402006-03-18 18:35:43 -05003932 struct cfq_data *cfqd = e->elevator_data; \
Linus Torvalds1da177e2005-04-16 15:20:36 -07003933 unsigned int __data; \
3934 int ret = cfq_var_store(&__data, (page), count); \
3935 if (__data < (MIN)) \
3936 __data = (MIN); \
3937 else if (__data > (MAX)) \
3938 __data = (MAX); \
3939 if (__CONV) \
3940 *(__PTR) = msecs_to_jiffies(__data); \
3941 else \
3942 *(__PTR) = __data; \
3943 return ret; \
3944}
3945STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
Jens Axboefe094d92008-01-31 13:08:54 +01003946STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
3947 UINT_MAX, 1);
3948STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
3949 UINT_MAX, 1);
Al Viroe572ec72006-03-18 22:27:18 -05003950STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
Jens Axboefe094d92008-01-31 13:08:54 +01003951STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
3952 UINT_MAX, 0);
Jens Axboe22e2c502005-06-27 10:55:12 +02003953STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
3954STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
3955STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
Jens Axboefe094d92008-01-31 13:08:54 +01003956STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
3957 UINT_MAX, 0);
Jens Axboe963b72f2009-10-03 19:42:18 +02003958STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
Vivek Goyalae30c282009-12-03 12:59:55 -05003959STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003960#undef STORE_FUNCTION
3961
Al Viroe572ec72006-03-18 22:27:18 -05003962#define CFQ_ATTR(name) \
3963 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
Jens Axboe3b181522005-06-27 10:56:24 +02003964
Al Viroe572ec72006-03-18 22:27:18 -05003965static struct elv_fs_entry cfq_attrs[] = {
3966 CFQ_ATTR(quantum),
Al Viroe572ec72006-03-18 22:27:18 -05003967 CFQ_ATTR(fifo_expire_sync),
3968 CFQ_ATTR(fifo_expire_async),
3969 CFQ_ATTR(back_seek_max),
3970 CFQ_ATTR(back_seek_penalty),
3971 CFQ_ATTR(slice_sync),
3972 CFQ_ATTR(slice_async),
3973 CFQ_ATTR(slice_async_rq),
3974 CFQ_ATTR(slice_idle),
Jens Axboe963b72f2009-10-03 19:42:18 +02003975 CFQ_ATTR(low_latency),
Vivek Goyalae30c282009-12-03 12:59:55 -05003976 CFQ_ATTR(group_isolation),
Al Viroe572ec72006-03-18 22:27:18 -05003977 __ATTR_NULL
Linus Torvalds1da177e2005-04-16 15:20:36 -07003978};
3979
Linus Torvalds1da177e2005-04-16 15:20:36 -07003980static struct elevator_type iosched_cfq = {
3981 .ops = {
3982 .elevator_merge_fn = cfq_merge,
3983 .elevator_merged_fn = cfq_merged_request,
3984 .elevator_merge_req_fn = cfq_merged_requests,
Jens Axboeda775262006-12-20 11:04:12 +01003985 .elevator_allow_merge_fn = cfq_allow_merge,
Divyesh Shah812d4022010-04-08 21:14:23 -07003986 .elevator_bio_merged_fn = cfq_bio_merged,
Jens Axboeb4878f22005-10-20 16:42:29 +02003987 .elevator_dispatch_fn = cfq_dispatch_requests,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003988 .elevator_add_req_fn = cfq_insert_request,
Jens Axboeb4878f22005-10-20 16:42:29 +02003989 .elevator_activate_req_fn = cfq_activate_request,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003990 .elevator_deactivate_req_fn = cfq_deactivate_request,
3991 .elevator_queue_empty_fn = cfq_queue_empty,
3992 .elevator_completed_req_fn = cfq_completed_request,
Jens Axboe21183b02006-07-13 12:33:14 +02003993 .elevator_former_req_fn = elv_rb_former_request,
3994 .elevator_latter_req_fn = elv_rb_latter_request,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003995 .elevator_set_req_fn = cfq_set_request,
3996 .elevator_put_req_fn = cfq_put_request,
3997 .elevator_may_queue_fn = cfq_may_queue,
3998 .elevator_init_fn = cfq_init_queue,
3999 .elevator_exit_fn = cfq_exit_queue,
Jens Axboefc463792006-08-29 09:05:44 +02004000 .trim = cfq_free_io_context,
Linus Torvalds1da177e2005-04-16 15:20:36 -07004001 },
Al Viro3d1ab402006-03-18 18:35:43 -05004002 .elevator_attrs = cfq_attrs,
Linus Torvalds1da177e2005-04-16 15:20:36 -07004003 .elevator_name = "cfq",
4004 .elevator_owner = THIS_MODULE,
4005};
4006
Vivek Goyal3e252062009-12-04 10:36:42 -05004007#ifdef CONFIG_CFQ_GROUP_IOSCHED
4008static struct blkio_policy_type blkio_policy_cfq = {
4009 .ops = {
4010 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
4011 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
4012 },
4013};
4014#else
4015static struct blkio_policy_type blkio_policy_cfq;
4016#endif
4017
Linus Torvalds1da177e2005-04-16 15:20:36 -07004018static int __init cfq_init(void)
4019{
Jens Axboe22e2c502005-06-27 10:55:12 +02004020 /*
4021 * could be 0 on HZ < 1000 setups
4022 */
4023 if (!cfq_slice_async)
4024 cfq_slice_async = 1;
4025 if (!cfq_slice_idle)
4026 cfq_slice_idle = 1;
4027
Linus Torvalds1da177e2005-04-16 15:20:36 -07004028 if (cfq_slab_setup())
4029 return -ENOMEM;
4030
Adrian Bunk2fdd82b2007-12-12 18:51:56 +01004031 elv_register(&iosched_cfq);
Vivek Goyal3e252062009-12-04 10:36:42 -05004032 blkio_policy_register(&blkio_policy_cfq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004033
Adrian Bunk2fdd82b2007-12-12 18:51:56 +01004034 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004035}
4036
4037static void __exit cfq_exit(void)
4038{
Peter Zijlstra6e9a4732006-09-30 23:28:10 -07004039 DECLARE_COMPLETION_ONSTACK(all_gone);
Vivek Goyal3e252062009-12-04 10:36:42 -05004040 blkio_policy_unregister(&blkio_policy_cfq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004041 elv_unregister(&iosched_cfq);
Al Viro334e94d2006-03-18 15:05:53 -05004042 ioc_gone = &all_gone;
OGAWA Hirofumifba82272006-04-18 09:44:06 +02004043 /* ioc_gone's update must be visible before reading ioc_count */
4044 smp_wmb();
Jens Axboed6de8be2008-05-28 14:46:59 +02004045
4046 /*
4047 * this also protects us from entering cfq_slab_kill() with
4048 * pending RCU callbacks
4049 */
Tejun Heo245b2e72009-06-24 15:13:48 +09004050 if (elv_ioc_count_read(cfq_ioc_count))
Jens Axboe9a11b4e2008-05-29 09:32:08 +02004051 wait_for_completion(&all_gone);
Konstantin Khlebnikov80b15c72010-05-20 23:21:41 +04004052 ida_destroy(&cic_index_ida);
Christoph Hellwig83521d32005-10-30 15:01:39 -08004053 cfq_slab_kill();
Linus Torvalds1da177e2005-04-16 15:20:36 -07004054}
4055
4056module_init(cfq_init);
4057module_exit(cfq_exit);
4058
4059MODULE_AUTHOR("Jens Axboe");
4060MODULE_LICENSE("GPL");
4061MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");